U.S. patent number 10,345,910 [Application Number 16/010,180] was granted by the patent office on 2019-07-09 for haptic actuator assembly with a spring pre-load device.
This patent grant is currently assigned to IMMERSION CORPORATION. The grantee listed for this patent is IMMERSION CORPORATION. Invention is credited to Juan Manuel Cruz Hernandez, Vahid Khoshkava, Kaniyalal Shah.
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United States Patent |
10,345,910 |
Khoshkava , et al. |
July 9, 2019 |
Haptic actuator assembly with a spring pre-load device
Abstract
A haptic actuator assembly includes a haptic actuator configured
to output displacement along a perpendicular axis and a pre-load
device. The pre-load device is disposed adjacent to the haptic
actuator and configured to generate a compressive load on the
haptic actuator along the perpendicular axis to oppose expansion of
the haptic actuator along the perpendicular axis. The pre-load
device includes a casing and at least a first spring component. The
casing includes a cover and a base spaced apart from and extending
parallel to the cover. The haptic actuator is disposed between the
cover and the base, and the first spring component is configured to
exert a force in order to create the compressive load on the haptic
actuator along the perpendicular axis.
Inventors: |
Khoshkava; Vahid (Montreal,
CA), Cruz Hernandez; Juan Manuel (Montreal,
CA), Shah; Kaniyalal (Fremont, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
IMMERSION CORPORATION |
San Jose |
CA |
US |
|
|
Assignee: |
IMMERSION CORPORATION (San
Jose, CA)
|
Family
ID: |
66676242 |
Appl.
No.: |
16/010,180 |
Filed: |
June 15, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B06B
1/0688 (20130101); H01L 41/09 (20130101); B06B
1/0238 (20130101); H01L 41/0536 (20130101); G06F
3/016 (20130101); B06B 1/0666 (20130101); B06B
2201/56 (20130101) |
Current International
Class: |
B60B
1/02 (20060101); B06B 1/06 (20060101); G06F
3/01 (20060101); B06B 1/02 (20060101) |
Field of
Search: |
;340/407.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
"Piezo Haptic Actuator, PowerHap.TM. 2.5G Type Preliminary Data"
pp. 1-9. cited by applicant .
"PowerHap.TM. Piezo actuators with haptic feedback, Technologies
& Products Press Conference 2016" pp. 1-16. cited by
applicant.
|
Primary Examiner: McNally; Kerri L
Attorney, Agent or Firm: Medler Ferro Woodhouse & Mills
PLLC
Claims
What is claimed is:
1. A haptic actuator assembly, comprising: a haptic actuator
including a layer of piezoelectric material configured to generate
strain along a parallel axis, the parallel axis being parallel to a
planar surface of the layer, and a displacement conversion device
configured to convert the strain of the layer of piezoelectric
material along the parallel axis to expansion or contraction of the
haptic actuator along a perpendicular axis, the perpendicular axis
being perpendicular to the planar surface of the layer, wherein the
expansion or contraction of the haptic actuator is configured to
generate a displacement of the haptic actuator along the
perpendicular axis; and a pre-load device adjacent to the haptic
actuator and configured to generate a compressive load on the
haptic actuator along the perpendicular axis, the pre-load device
including a casing having a cover and a base spaced apart from and
extending parallel to the cover, wherein the haptic actuator is
disposed between the cover and the base, the cover and the base
being disposed at respective opposite ends of the haptic actuator
along the perpendicular axis thereof, and a first spring component
disposed within the casing such that a first end of the first
spring component is coupled to an interior surface of the cover and
a second opposing end of the first component is coupled to an outer
surface of the haptic actuator, the first spring component being
configured to exert a force in order to create the compressive load
on the haptic actuator along the perpendicular axis.
2. The haptic actuator assembly of claim 1, wherein the
displacement conversion device of the haptic actuator is a
displacement amplification device configured to convert a
displacement output by the layer of piezoelectric material along
the parallel axis due to the strain thereof to a greater
displacement of the haptic actuator along the perpendicular
axis.
3. The haptic actuator assembly of claim 2, wherein the
displacement amplification device of the haptic actuator includes a
lever device configured to convert the displacement along the
parallel axis to the greater displacement along the perpendicular
axis.
4. The haptic actuator assembly of claim 3, wherein the lever
device of the haptic actuator includes a first disc and a second
disc disposed on respective opposite planar surfaces of the layer
of piezoelectric material, wherein each disc of the first disc and
the second disc forms a truncated cone with a respective planar
surface of the layer of piezoelectric material.
5. The haptic actuator assembly of claim 1, wherein the first
spring component is a spring plunger.
6. The haptic actuator assembly of claim 1, wherein the first
spring component includes a screw and a flexible film component,
the screw being configured to adjust a spring force of the flexible
film component.
7. The haptic actuator assembly of claim 1, wherein the pre-load
device further includes a second spring component disposed within
the casing such that a first end of the second spring component is
coupled to an interior surface of the base and a second opposing
end of the second spring component is coupled to an outer surface
of the haptic actuator, the first spring component and the second
spring component being configured to collectively exert the force
in order to create the compressive load on the haptic actuator
along the perpendicular axis.
8. The haptic actuator assembly of claim 7, wherein the first
spring component has a first spring constant and the second spring
component has a second spring constant, the first spring constant
being different than the second spring constant.
9. The haptic actuator assembly of claim 1, wherein the compressive
load along the perpendicular axis generated by the first component
and the second component of the pre-load device is in a range of 2
N to 4 N.
10. The haptic actuator assembly of claim 1, wherein the haptic
actuator further comprises at least two electrodes attached to or
embedded within the layer of piezoelectric material and configured
to create a voltage difference along the perpendicular axis,
wherein the layer of piezoelectric material is configured to
contract along the parallel axis in response to the voltage
difference along the perpendicular axis.
11. The haptic actuator assembly of claim 10, wherein when the
voltage difference between the at least two electrodes is between
50 V and 100 V and when the compressive load is applied to the
haptic actuator by the pre-load device, the haptic actuator outputs
a displacement along the perpendicular axis, relative to a baseline
state in which there is no voltage difference between the at least
two electrodes, that is in a range of 1 .mu.m to 15 .mu.m, and the
haptic actuator assembly is configured to output a force along the
perpendicular axis that is in a range of 2 N to 10 N.
12. The haptic actuator assembly of claim 1, wherein the haptic
actuator has a first resonant frequency and the haptic actuator
assembly has a second resonant frequency, the second resonant
frequency being different than the first resonant frequency and the
second resonant frequency being determined via a spring constant of
the first spring component.
13. A haptic actuator assembly, comprising: a haptic actuator
including a layer of piezoelectric material configured to generate
strain along a parallel axis, the parallel axis being parallel to a
planar surface of the layer, and a displacement conversion device
configured to convert the strain of the layer of piezoelectric
material along the parallel axis to expansion or contraction of the
haptic actuator along a perpendicular axis, the perpendicular axis
being perpendicular to the planar surface of the layer, wherein the
expansion or contraction of the haptic actuator is configured to
generate a displacement of the haptic actuator along the
perpendicular axis; and a pre-load device adjacent to the haptic
actuator and configured to generate a compressive load on the
haptic actuator along the perpendicular axis, the pre-load device
including a casing having a cover, a base spaced apart from and
extending parallel to the cover, a first spring component, and a
second spring component, wherein the first spring component and the
second spring component are disposed at respective opposite ends of
the cover and each of the first spring component and the second
spring component extends between the cover and the base, and
wherein the first spring component and the second spring component
are configured to collectively exert a force in order to create the
compressive load on the haptic actuator along the perpendicular
axis, and wherein the haptic actuator is disposed between the cover
and the base, the cover and the base being disposed at respective
opposite ends of the haptic actuator along the perpendicular axis
thereof.
14. The haptic actuator assembly of claim 13, wherein the first
spring component and the second spring component are attached to
the cover and are releasably attached to the base.
15. A haptic-enabled device, comprising: a housing; a power source;
a haptic actuator assembly configured to generate a haptic effect
at an outer surface of the housing, the haptic actuator assembly
comprising a haptic actuator including a layer of piezoelectric
material configured to generate strain along a parallel axis, the
parallel axis being parallel to a planar surface of the layer, at
least two electrodes attached to or embedded within the layer of
piezoelectric material, and a displacement conversion device
configured to convert the strain of the layer of piezoelectric
material along the parallel axis to expansion or contraction of the
haptic actuator along a perpendicular axis, the perpendicular axis
being perpendicular to the planar surface of the layer, wherein the
expansion or contraction of the haptic actuator is configured to
generate a displacement of the haptic actuator along the
perpendicular axis; a pre-load device adjacent to the haptic
actuator and configured to generate a compressive load on the
haptic actuator along the perpendicular axis, the pre-load device
including a casing having a cover and a base spaced apart from and
extending parallel to the cover, wherein the haptic actuator is
disposed between the cover and the base, the cover and the base
being disposed at respective opposite ends of the haptic actuator
along the perpendicular axis thereof, and a first spring component
disposed within the casing such that a first end of the first
spring component is coupled to an interior surface of the cover and
a second opposing end of the first component is coupled to an outer
surface of the haptic actuator, the first spring component being
configured to exert a force in order to create the compressive load
on the haptic actuator along the perpendicular axis; and a control
unit configured to control the power source to provide power to the
at least two electrodes of the haptic actuator.
16. The haptic-enabled device of claim 15, wherein any compressive
load applied to the haptic actuator assembly by the housing of the
haptic-enabled device is less than 1 N.
17. The haptic-enabled device of claim 15, further comprising a
touch screen device that forms a first side of the housing, wherein
the housing comprises a back panel that forms a second and opposite
side of the housing, wherein the haptic actuator assembly is
disposed at the second side of the housing, so that force generated
by the haptic actuator assembly is exerted against the second side
of the housing.
18. The haptic-enabled device of claim 17, wherein the control unit
is configured to control the power source to provide a drive signal
to the haptic actuator and wherein the drive signal is a periodic
signal having a frequency equal to a resonant frequency of the
haptic actuator assembly.
19. The haptic-enabled device of claim 18, wherein the haptic
actuator has a first resonant frequency and the haptic actuator
assembly has a second resonant frequency, the second resonant
frequency being different than the first resonant frequency and the
second resonant frequency being determined via a spring constant of
the first spring component.
20. The haptic-enabled device of claim 15, wherein the pre-load
device further includes a second spring component disposed within
the casing such that a first end of the second spring component is
coupled to an interior surface of the base and a second opposing
end of the second spring component is coupled to an outer surface
of the haptic actuator, the first spring component and the second
spring component being configured to collectively exert the force
in order to create the compressive load on the haptic actuator
along the perpendicular axis.
Description
FIELD OF THE INVENTION
The present invention is directed to a haptic actuator assembly
with a mechanical pre-load device that has application in gaming,
consumer electronics, automotive, entertainment, and other
industries.
BACKGROUND
Haptics provide a tactile and force feedback technology that takes
advantages of a user's sense of touch by applying haptic effects,
such as forces, vibrations, and other motions to a user. Devices
such as mobile devices, tablet computers, and handheld game
controllers can be configured to generate haptic effects. Haptic
effects can be generated with haptic actuators, such as an
eccentric rotating mass (ERM) actuator or a linear resonant
actuator (LRA). The haptic effects may include a vibrotactile
haptic effect that provides a vibration at a surface or other
portion of such devices.
SUMMARY
One aspect of embodiments described herein relates to a haptic
actuator assembly including a haptic actuator and a pre-load
device. The haptic actuator includes a layer of piezoelectric
material configured to generate strain along a parallel axis, the
parallel axis being parallel to a planar surface of the layer, and
includes a displacement conversion device configured to convert the
strain of the layer of piezoelectric material along the parallel
axis to expansion or contraction of the haptic actuator along a
perpendicular axis, the perpendicular axis being perpendicular to
the planar surface of the layer. The expansion or contraction of
the haptic actuator is configured to generate a displacement of the
haptic actuator along the perpendicular axis. The pre-load device
is adjacent to the haptic actuator and configured to generate a
compressive load on the haptic actuator along the perpendicular
axis. The pre-load device includes a casing having a cover and a
base spaced apart from and extending parallel to the cover. The
haptic actuator is disposed between the cover and the base, the
cover and the base being disposed at respective opposite ends of
the haptic actuator along the perpendicular axis thereof. A first
spring component is disposed within the casing such that a first
end of the first spring component is coupled to an interior surface
of the cover and a second opposing end of the first component is
coupled to an outer surface of the haptic actuator. The first
spring component is configured to exert a force in order to create
the compressive load on the haptic actuator along the perpendicular
axis.
Another aspect of the embodiments herein relates to a haptic
actuator assembly including a haptic actuator and a pre-load
device. The haptic actuator includes a layer of piezoelectric
material configured to generate strain along a parallel axis, the
parallel axis being parallel to a planar surface of the layer, and
includes a displacement conversion device configured to convert the
strain of the layer of piezoelectric material along the parallel
axis to expansion or contraction of the haptic actuator along a
perpendicular axis, the perpendicular axis being perpendicular to
the planar surface of the layer. The expansion or contraction of
the haptic actuator is configured to generate a displacement of the
haptic actuator along the perpendicular axis. The pre-load device
is adjacent to the haptic actuator and configured to generate a
compressive load on the haptic actuator along the perpendicular
axis. The pre-load device includes a casing having a cover, a base
spaced apart from and extending parallel to the cover, a first
spring component, and a second spring component. The first spring
component and the second spring component are disposed at
respective opposite ends of the cover and each of the first spring
component and the second spring component extends between the cover
and the base. The first spring component and the second spring
component are configured to collectively exert a force in order to
create the compressive load on the haptic actuator along the
perpendicular axis. The haptic actuator is disposed between the
cover and the base, the cover and the base being disposed at
respective opposite ends of the haptic actuator along the
perpendicular axis thereof.
Another aspect of the embodiments herein relates to is a
haptic-enabled device including a housing, a power source, a
control device, and a haptic actuator assembly configured to
generate a haptic effect at an outer surface of the housing. The
haptic actuator includes a layer of piezoelectric material
configured to generate strain along a parallel axis, the parallel
axis being parallel to a planar surface of the layer, and includes
at least two electrodes attached to or embedded within the layer of
piezoelectric material, and includes a displacement conversion
device configured to convert the strain of the layer of
piezoelectric material along the parallel axis to expansion or
contraction of the haptic actuator along a perpendicular axis, the
perpendicular axis being perpendicular to the planar surface of the
layer. The expansion or contraction of the haptic actuator is
configured to generate a displacement of the haptic actuator along
the perpendicular axis. The pre-load device is adjacent to the
haptic actuator and configured to generate a compressive load on
the haptic actuator along the perpendicular axis. The pre-load
device includes a casing having a cover and a base spaced apart
from and extending parallel to the cover. The haptic actuator is
disposed between the cover and the base, the cover and the base
being disposed at respective opposite ends of the haptic actuator
along the perpendicular axis thereof. A first spring component is
disposed within the casing such that a first end of the first
spring component is coupled to an interior surface of the cover and
a second opposing end of the first component is coupled to an outer
surface of the haptic actuator. The first spring component is
configured to exert a force in order to create the compressive load
on the haptic actuator along the perpendicular axis. The control
unit is configured to control the power source to provide power to
the at least two electrodes of the haptic actuator.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other features, objects and advantages of the
invention will be apparent from the following detailed description
of embodiments hereof as illustrated in the accompanying drawings.
The accompanying drawings, which are incorporated herein and form a
part of the specification, further serve to explain the principles
of the invention and to enable a person skilled in the pertinent
art to make and use the invention. The drawings are not to
scale.
FIG. 1 depicts a block diagram of a haptic-enabled device having a
haptic actuator assembly, according to an embodiment hereof.
FIGS. 2A and 2B depict block diagrams of a haptic actuator assembly
and a haptic actuator, according to embodiments hereof.
FIGS. 3A and 3B depict a haptic-enabled device and a haptic
actuator assembly disposed on a back side of the haptic-enabled
device, according to an embodiment hereof.
FIG. 4 depicts a haptic actuator assembly disposed within a back
panel of a housing of a haptic actuator assembly, according to an
embodiment hereof.
FIG. 5 depicts a block diagram of a haptic-enabled system that
includes a touch screen device, a haptic actuator assembly, and a
mounting component, according to an embodiment hereof.
FIG. 6 depicts a haptic-enabled system that includes a touch screen
device, a haptic actuator assembly, and a mounting component,
according to an embodiment hereof.
FIGS. 7A and 7B depict a haptic actuator assembly with a haptic
actuator and a pre-load device, according to an embodiment
hereof.
FIGS. 8A-8E depict an example haptic actuator for a haptic actuator
assembly, according to an embodiment hereof.
FIG. 9 depicts an example haptic actuator for a haptic actuator
assembly, according to an embodiment hereof.
FIG. 10 depicts a haptic actuator assembly with a haptic actuator
and a pre-load device, according to an embodiment hereof.
FIG. 11 depicts a perspective view of a haptic actuator assembly
with a haptic actuator and a pre-load device, wherein the pre-load
device includes a casing and a first spring component, according to
an embodiment hereof.
FIG. 12 depicts a sectional side view of the haptic actuator
assembly of FIG. 11.
FIG. 13 depicts a sectional side view of a haptic actuator assembly
with a haptic actuator and a pre-load device, wherein the pre-load
device includes a casing, a first spring component and a second
spring component, according to an embodiment hereof.
FIG. 14 depicts a perspective view of a haptic actuator assembly
with a haptic actuator and a pre-load device, wherein the pre-load
device includes a casing and a first spring component that includes
a spring plunger, according to an embodiment hereof.
FIG. 15 depicts a perspective view of a haptic actuator assembly
with a haptic actuator and a pre-load device, wherein the pre-load
device includes a casing and a first spring component that includes
a screw and a flexible film component, according to an embodiment
hereof.
FIG. 16A depicts a sectional side view of a cover that includes a
first spring component and a second spring component, wherein the
cover forms a portion of a casing of a pre-load device according to
an embodiment hereof.
FIG. 16B depicts a sectional side view of a haptic actuator
assembly with a haptic actuator and a pre-load device, wherein the
pre-load device includes a casing that includes the cover of FIG.
16A and a base, according to an embodiment hereof.
FIG. 17 depicts a sectional side view of a haptic actuator assembly
with a haptic actuator and a pre-load device, wherein the pre-load
device includes a casing, a first spring component and a second
spring component, according to an embodiment hereof.
FIG. 18 provides a graph that depicts an example relationship
between force that is output by a haptic actuator and displacement
that is output by the haptic actuator, according to an embodiment
hereof.
DETAILED DESCRIPTION
The following detailed description is merely exemplary in nature
and is not intended to limit the invention or the application and
uses of the invention. Furthermore, there is no intention to be
bound by any expressed or implied theory presented in the preceding
technical field, background, brief summary or the following
detailed description.
One aspect of the embodiments herein relates to providing a
pre-load device for a haptic actuator assembly. The haptic actuator
assembly may include a haptic actuator, such as a piezoelectric
actuator, that is configured to output displacement (e.g., strain
or other deformation) and force. In one example, the displacement
may be used to generate a vibrotactile haptic effect, by
oscillating between a first displacement value and a second
displacement value. The pre-load device may be configured to
generate a pre-load on the haptic actuator that constrains the
displacement provided by the haptic actuator. The constraint may
still allow the haptic actuator to output displacement, but reduces
an amplitude of the displacement relative to a situation in which
the pre-load device is absent. In some instances, the displacement
may take the form of strain that causes the haptic actuator to
expand along a particular axis, and the pre-load generated by the
pre-load device may be a compressive load that opposes expansion of
the haptic actuator along that axis. In some instances, the
pre-load may be a load that is independent of user interaction or
influences that are external to the haptic actuator assembly. In
other words, the pre-load may be a load that is, e.g., built into
the haptic actuator assembly or internal to the haptic actuator
assembly. The pre-load may constrain a displacement from the haptic
actuator, an amount of change in the displacement of the haptic
actuator, or a combination thereof.
In an embodiment, the pre-load device may constrain or otherwise
oppose displacement from the haptic actuator in order to prevent a
force that is also output by the haptic actuator from becoming too
weak. For instance, the haptic actuator may have a
force-displacement profile like that in FIG. 18, in which the
haptic actuator outputs less force as it outputs more displacement,
and vice versa. If no pre-load is applied to the haptic actuator
when the haptic actuator is driven with a drive signal or other
stimulus, the haptic actuator may in some instances output a
displacement that is equal to a rated displacement d.sub.rated
(also referred to as nominal displacement) that is associated with
the haptic actuator and with an amplitude of the drive signal. For
instance, the haptic actuator may be a piezoelectric actuator. When
a drive signal is applied to the piezoelectric actuator, the
piezoelectric actuator may output a strain along a particular axis
that is equal to a rated displacement (e.g., rated strain). When
the amount of displacement provided by the haptic actuator is equal
to the rated displacement, however, the displacement may be
accompanied by little to no force. For example, FIG. 18 illustrates
a situation in which a haptic actuator outputs a displacement that
oscillates in value near a rated displacement of the haptic
actuator (e.g., as a result of being driven by an oscillating drive
signal). The haptic actuator may output such displacement because
of an absence of a pre-load or of an external load. The oscillating
displacement may translate into a vibrotactile haptic effect, but
the vibrotactile haptic effect may be accompanied by only a small
amount of force, as depicted in FIG. 18. As a result, the
vibrotactile haptic effect may be perceived by a user as being very
weak, or may not be perceived at all.
FIG. 18 further illustrates another situation in which a haptic
actuator generates displacement in the presence of a pre-load. The
displacement in both situations in FIG. 18 may be generated by the
same signal amplitude or the same drive signal. In an embodiment,
the pre-load may constrain the displacement from the haptic
actuator to a value that is a fraction (e.g., 1/2, 3/4) of its
rated displacement. As an example, the pre-load may constrain
displacement that is output by the haptic actuator such that the
displacement is reduced from 35 .mu.m (when the pre-load is absent)
to 1 .mu.m (when the pre-load is present). By decreasing the
displacement, the pre-load can cause an increase in the force
output by the haptic actuator. As a result, if a vibrotactile
haptic effect is generated by a haptic actuator assembly that
includes the pre-load, the force accompanying the vibrotactile
haptic effect may be stronger and more perceivable relative to the
situation in which the vibrotactile haptic effect is generated by a
haptic actuator having no pre-load.
In an embodiment, the pre-load device may constrain or otherwise
oppose displacement from the haptic actuator in order to protect
the haptic actuator. For instance, a haptic actuator that includes
piezo ceramic material may be brittle and thus may suffer cracking
or other damage from excessive strain or other displacement. In
such an instance, the pre-load device may constrain a range of
motion from the haptic actuator by constraining its displacement,
and thus may guard against the haptic actuator suffering damage
associated with excessive strain. Stated another way, the pre-load
device may protect the haptic actuator by opposing excessive
displacement from the haptic actuator.
In an embodiment, the pre-load device may be a mechanical in nature
and may be configured to generate a pre-load via a spring force or
spring forces. Stated another way, the pre-load device may include
at least one spring component that generates a spring force to
provide a pre-load on the haptic actuator. The spring force or
spring forces may, e.g., generate a compressive load that opposes
expansion of the haptic actuator along one or more axes of motion.
A spring component is utilized to compress the haptic actuator, and
thereby pre-load the haptic actuator, and the total stiffness of
the system is thereby changed. The displacement output by the
haptic actuator is a function of the stiffness of the system, and
thus the spring component constrains or reduces the displacement or
strain from the haptic actuator.
In an embodiment, a haptic actuator assembly having the pre-load
device may be disposed at a location at which the haptic actuator
assembly will experience little to no external load. For instance,
the haptic actuator assembly may be disposed at a back side of a
mobile phone, such as on an inner surface of a back panel of the
mobile phone. The back panel may have a low mass (e.g., less than 1
g), and may exert less than 1 N of external load on the haptic
actuator assembly. In such a situation, the pre-load device may
advantageously provide a pre-load to constrain displacement of a
haptic actuator of the assembly.
FIG. 1 depicts a block diagram of a haptic-enabled device 100 that
may include a haptic actuator assembly 120 that incorporates a
pre-load device. More specifically, the haptic-enabled device 100
includes a housing 110, the haptic actuator assembly 120, a control
unit 130, and a power source 140. In an embodiment, the
haptic-enabled device 100 may be a user interface device such as a
mobile phone, tablet computer, laptop, handheld game controller,
wearable device (e.g., haptic-enabled electronic watch, glove, or
head-mounted device) or any other user interface device.
In an embodiment, the power source 140 may include a battery or
other energy storage device that is configured to provide power for
the haptic actuator assembly 120 to generate a haptic effect (the
terms power and energy are used interchangeably herein). In an
embodiment, the control unit 130 may be configured to control the
power source 140 to drive a haptic actuator, which is described
below in more detail, of the haptic actuator assembly 120. For
instance, the control unit 130 may be configured to control the
power source 140 to generate a drive voltage signal or a drive
current signal to be applied to the haptic actuator of the haptic
actuator assembly 120. The power source 140 may be configured to
generate a drive signal for the haptic actuator of the haptic
actuator assembly 120 that has an amplitude in a range of 50 V to
100 V (e.g., a 60 V drive signal).
In an embodiment, the control unit 130 may be dedicated to
controlling the generating of haptic effects on the haptic-enabled
device 100, or may be a general purpose control unit that controls
other operations on the haptic-enabled device 100. In an
embodiment, the control unit 130 may include one or more
microprocessors, one or more processing cores, a programmable logic
array (PLA), a field programmable gate array (FPGA), an application
specific integrated circuit (ASIC), or any other processing
circuit.
FIG. 2A illustrates a block diagram of a haptic actuator assembly
120A that is an embodiment of the haptic actuator assembly 120. The
haptic actuator assembly 120A includes a haptic actuator 121 and a
pre-load device 127. The pre-load device 127 is described below in
more detail. In an embodiment, the pre-load device may be
configured to generate a compressive load that is in a range of 2 N
to 4 N. In an embodiment, the haptic actuator 121 is configured to
output displacement and force along a particular axis. For
instance, the haptic actuator 121 may be a piezoelectric actuator,
or an electroactive polymer (EAP) actuator, such as an EAP actuator
that includes polyvinylidene difluoride (PVDF). In an embodiment,
the haptic actuator 121 may be configured to exhibit strain or
other deformation that expands or shrinks the haptic actuator along
one or more axes.
FIG. 2B depicts a block diagram of an embodiment of the haptic
actuator 121. In the embodiment of FIG. 2B, the haptic actuator 121
includes a piezoelectric layer 121a (also referred to as a layer of
piezoelectric material or a sheet of piezoelectric material),
electrodes 121b, and a displacement conversion device 121c. The
piezoelectric layer 121a may be connected to the electrodes 121b,
and may be configured to output strain along one or more axes when
a drive signal is applied to the electrodes 121b. In some cases,
the piezoelectric layer 121 may include a stack of sub-layers of
piezoelectric material, wherein each of the sub-layers is directly
sandwiched between two electrodes of the electrodes 121b. In other
cases, the piezoelectric layer 121a has only one such
sub-layer.
In an embodiment, the displacement conversion device 121c may be
configured to convert strain or other displacement that is along a
first axis (e.g., an x-axis) to displacement that is along a second
axis (e.g., a z-axis). In an embodiment, the first axis may be a
parallel axis, wherein the parallel axis is parallel to a planar
surface of the piezoelectric layer 121a. In an embodiment, the
second axis may be a perpendicular axis, wherein the perpendicular
axis is perpendicular to the planar surface of the piezoelectric
layer 121a. In some cases, the displacement conversion device 121c
may be a displacement amplification device that is configured to
amplify a displacement along the first axis (e.g., .DELTA.x) to a
greater displacement (e.g., .DELTA.z) along the second axis.
FIGS. 3A and 3B depict a haptic-enabled device 200 that is an
embodiment of the haptic-enabled device 100. The haptic-enabled
device 200 may be, e.g., a mobile phone or a tablet computer. The
haptic-enabled device 200 may comprise a housing 210 that is formed
by at least a front panel 212 and a back panel 214. The front panel
212 may form a front side of the housing 210, and may incorporate a
touch screen device 213, such as a liquid crystal display (LCD) or
light emitting display (LED) that has capacitive or resistive touch
sensors. The back panel 214 may form a back side of the housing
210. The front side of the housing 210 may be a side that generally
faces a user during use, while the back side is disposed opposite
of, or opposing, the front side of the housing 210.
As illustrated in FIG. 3B, the haptic-enabled device 200 further
includes a haptic actuator assembly 220. In some embodiments, the
haptic actuator assembly 220 is disposed within the back panel 214,
or on an inner surface or outer surface of the back panel 214. For
instance, FIG. 4 depicts an embodiment in which the back panel 214
has a cavity 214a, and the haptic actuator assembly 220 is embedded
within the back panel 214 by being disposed within the cavity 214a.
The haptic actuator assembly 220 may be configured to, e.g.,
generate a vibrotactile haptic effect at an outer or exterior
surface 214b of the back panel 214. The vibrotactile haptic effect
may be generated when the haptic actuator assembly repeatedly
expands and contracts along an axis 217 in FIG. 4 at a certain
frequency in order to output an oscillating displacement (also
referred to as oscillating vibration or oscillating movement) along
the axis 217. More generally speaking, the vibrotactile haptic
effect may be generated when the haptic actuator assembly generates
a time-varying amount of displacement, such as a displacement that
oscillates in value at a particular frequency. When the haptic
actuator assembly 220 is outputting displacement, it may press
against, or pull on, a sub-layer 214c of the back panel 214. The
sub-layer 214c may be of a material having a suitable Young's
modulus and may be sufficiently thin to be able to undergo elastic
bending or other elastic deformation as a result of being acted
upon by the haptic actuator assembly 220, such as by being pressed
or pulled by the assembly. In other words, the sub-layer 214c of
the back panel 214 may be configured to have a stiffness that
permits it to bend inward and outward relative to a remainder of
the back panel 214, as illustrated by the dashed lines in FIG. 4,
to generate a vibrotactile haptic effect.
As discussed in more detail below, the haptic actuator assembly 220
may include a pre-load device that constrains expansion by the
haptic actuator assembly along an axis, such as the axis 217. The
sub-layer 214c, or more generally the back panel 214, may by itself
lack sufficient stiffness to constrain expansion of the haptic
actuator assembly 220. For instance, any compressive load applied
to the haptic actuator assembly 220 by the sub-layer 214c, or more
generally by the back panel 214, may be less than 1 N. More
generally speaking, any compressive load applied to the haptic
actuator assembly 220 by the housing 210 may be less than 1 N. In
some cases, the housing may apply no compressive load on the haptic
actuator assembly 220. In such a situation, the absence of a
pre-load may allow an amount of displacement that is output from
the haptic actuator of the haptic actuator assembly to be
excessive, wherein the excessive displacement may reduce a force of
the vibrotactile haptic effect at the outer surface 214b and may
increase a risk of damage to the haptic actuator of the haptic
actuator assembly 220. Thus, a pre-load device in accordance
herewith may be advantageous in such an application to constrain
displacement along the axis 217 of the haptic actuator assembly
220, and particularly displacement of its haptic actuator along the
axis 217.
In an embodiment, a displacement that is output by the haptic
actuator assembly 220 may be generated by a haptic actuator of the
haptic actuator assembly. For instance, if a haptic actuator of the
haptic actuator assembly 220 expands by 5 .mu.m along the axis 217,
such that the haptic actuator is outputting a displacement of 5
.mu.m, the haptic actuator assembly 220 may also expand by 5 .mu.m,
such that the haptic actuator assembly 220 is also outputting 5
.mu.m of displacement. Accordingly, the amount of displacement by
the haptic actuator and the amount of displacement by the haptic
actuator assembly 220 may be the same, or may be different.
In an embodiment, a force that is output by the haptic actuator
assembly 220, such as a force exerted against the sub-layer 214c,
may be equal to a force generated by a haptic actuator of the
assembly 220 minus a force of any pre-load. For instance, the
haptic actuator assembly 220 may generate a pre-load of 4 N. The
pre-load may be a compressive load against the haptic actuator that
causes, or results in, the haptic actuator generating a force that
is about 20 N. In some instances, a force that is output by the
haptic actuator assembly may be about 16 N.
In an embodiment, the haptic-enabled device 200 illustrated in FIG.
4 may further include a rigid component 218 that is disposed on an
inner surface 214d of the back panel 214. More specifically, the
rigid component 218 may be in contact with the inner surface 214d.
The rigid component 218 may channel displacement from the haptic
actuator assembly 220 toward the outer surface 214b of the back
panel 214, rather than toward the inner surface 214d. More
specifically, the rigid component 218 may be incompressible along
the axis 217, such that when the haptic actuator of the haptic
actuator assembly 220 expands along the axis 217, the sub-layer
214c provides much less resistance against that expansion than does
the rigid component 218. As a result, most or all of the expansion
of the haptic actuator of the assembly 220 may be channeled toward
bending the sub-layer 214c, rather than toward compressing the
rigid component 218. Examples of the rigid component 218 may
include a metal frame, a printed circuit board (PCB) substrate, or
a rigid battery shell.
In an embodiment, a haptic actuator assembly of the embodiments
herein may be part of a haptic-enabled system, such as the
haptic-enabled system 300 of FIG. 5. In an embodiment, the
haptic-enabled system 300 may be a center console system for
providing various in-vehicle functionality, including displaying
navigation instructions, providing entertainment options, and
displaying sensor data. In an embodiment, the haptic-enabled system
300 includes a touch screen device 310, a haptic actuator assembly
320, a control unit 330, a power source 340, and a mounting
component 350. The control unit 330 may be similar to the control
unit 130 of FIG. 1, and the power source 340 may be similar to the
power source 140. The touch screen device 310 may be, for instance,
a capacitive or resistive LCD or LED touch screen configured to
receive touch input.
Like the haptic actuator assembly 120 or 220, the haptic actuator
assembly 320 may be configured to output displacement and force to
generate a haptic effect at the touch screen device 310. The haptic
actuator assembly 320 may include a pre-load device to constrain
displacement so that a sufficient amount of force accompanies the
displacement. The touch screen device 310 may be directly or
indirectly connected to a mounting component 350. In an embodiment,
the mounting component 350 may be part of a body of a vehicle's
center console.
FIG. 6 depicts a haptic-enabled system 400 that is an embodiment of
the haptic-enabled system 300. The haptic-enabled system 400
includes a touch screen device 410, a haptic actuator assembly 420,
and a mounting component 450. In an embodiment, the touch screen
device 410 may have a mass of less than 10 g. The haptic actuator
assembly 420 may be configured to output displacement along an axis
417. As a result, the haptic actuator assembly 420 may press/push
and pull against a surface 410a of the touch screen device 410 to
generate a vibrotactile haptic effect at an exterior surface 410b
of the touch screen device 410. The surface 410b may be a front
exterior surface facing a driver, while the surface 410a may be an
opposite surface of the touch screen device 410. In an embodiment,
the mounting component 450 may be a rigid component, and may have
substantially more mass than the touch screen device 410, such that
most or all of the displacement that is output by the haptic
actuator assembly 420 is directed toward moving the touch screen
device 410, rather than toward moving the mounting component 450.
In an embodiment, the touch screen device 410 may be connected to
the mounting component 450 via the haptic actuator assembly 420. In
an embodiment, the touch screen device 410 may be connected to the
mounting component 450 via a suspension that allows the touch
screen 410 to move along the axis 417.
In an embodiment, the haptic actuator assembly 420 may include a
pre-load device that constrains expansion of the haptic actuator
assembly 420 along the axis 417. In the embodiment of FIG. 6, a
weight W of the touch screen device 410 may not provide sufficient
load by itself to provide a sufficient compressive load on the
haptic actuator assembly 420 along the axis 417. As depicted in
FIG. 6, the weight W may be insufficient because it is too low in
magnitude (because the mass of the touch screen device 410 is low),
and/or the weight W is acting in a direction that is partially or
completely perpendicular to the axis 417. In such an application, a
pre-load device in accordance herewith may be incorporated into the
haptic actuator assembly 420 in order to constrain the expansion of
the haptic actuator assembly.
An embodiment of a haptic actuator assembly 520 is illustrated in
FIGS. 7A and 7B. The haptic actuator assembly 520 includes a haptic
actuator 521 and a pre-load device 527. As depicted in FIG. 7B, the
haptic actuator 521 may be configured to output displacement along
an axis 517 by expanding along the axis 517. The displacement that
is output by the haptic actuator 521 may become the displacement
that is output by the haptic actuator assembly 520 as a whole. In
an embodiment, the axis 517 may represent a thickness dimension of
the haptic actuator assembly 520, and the displacement that is
output by the haptic actuator assembly 520 may refer to a change in
a thickness, or .DELTA.t, of the haptic actuator assembly 520
relative to, e.g., a baseline state in which the haptic actuator
521 was not activated. In an embodiment, the haptic actuator 521
may be a piezoelectric actuator.
In an embodiment, the pre-load device 527 includes at least a first
component 527a and a second component 527b that are configured to
generate a pre-load, which may be in the form of a compressive
load, as represented by arrows 560 in FIGS. 7A and 7B, opposing
expansion along the axis 517 of the haptic actuator 521 and of the
haptic actuator assembly 520. The haptic actuator 521 is sandwiched
or otherwise disposed between the first component 527a and the
second component 527b. In an embodiment, the first component 527a
and the second component 527b may be attached to opposing sides of
the haptic actuator 521 via an adhesive or some other manner of
attachment. In an embodiment, the first component 527a and the
second component 527b may be held in contact or in close proximity
to opposing sides of the haptic actuator 521 without being fixedly
attached thereto. In some cases, the compressive load may be
generated by a spring force or forces. As discussed below in more
detail, the pre-load device 527 may include one or more spring
components configured to generate a spring force(s) onto the haptic
actuator 521.
FIGS. 8A-8D illustrate a haptic actuator 621 that is an embodiment
of the haptic actuator 521. In this embodiment, the haptic actuator
621 is a piezoelectric actuator that includes a layer 621a of
piezoelectric material configured to generate a strain along an
axis, such as axis 618 and/or axis 619, that is parallel to a
planar surface (e.g., 621a-1 or 621a-2) of the layer 621a. In an
embodiment, the layer 621a of piezoelectric material may have a
length L that is in a range of 9 mm to 25 mm, a width W that is in
a range of 9 mm to 25 mm, and a thickness T.sub.2 (see FIG. 8B)
that is in a range of 0.3 mm to 2 mm. In an embodiment, as depicted
in FIG. 8A, the length L and the width W of the layer 621a may both
be equal to each other. In an embodiment, the layer 621a of
piezoelectric material is a layer of lead zirconate titanate (PZT)
or other piezo ceramic material. In an embodiment, the layer 621a
of piezoelectric material is a layer of polymer. In an embodiment,
as illustrated in FIG. 8B, the haptic actuator 621 may have an
overall thickness T.sub.1 that is in a range of 1 mm to 4 mm. In an
embodiment, the haptic actuator 621 may be a version of the
TDK.RTM. PowerHap.TM. piezo actuator, such as the Miniaturized
PowerHap.TM. 2.5G type of haptic actuator from TDK.RTM..
As illustrated in FIGS. 8A-8C, the haptic actuator 621 further
includes a displacement conversion device 621b-1/621b-2 that is
configured to convert strain along an axis, such as axis 618 or
axis 619, to expansion or contraction of the haptic actuator 621
along an axis 617, which is perpendicular to the planar surface
(e.g., surface 621a-1 or 621a-2) of the layer 621a of piezoelectric
material. The axis 618 or 619 may be referred to as a parallel
axis, while the axis 617 may be referred to as a perpendicular
axis. In an embodiment, the displacement that is output by the
haptic actuator 621 along the axis 617 may arise from the expansion
or contraction of the haptic actuator 621 along the axis 617.
In an embodiment, the displacement conversion device 621b-1/621b-2
is a displacement amplification device configured to convert a
displacement, i.e., a first amount of displacement, caused by the
strain along the axis 618 or axis 619, to a greater amount of
displacement, i.e., a second amount of displacement, along the axis
617, wherein the second displacement is greater than the first
displacement (see FIG. 8C). The displacement that is output by the
haptic actuator 621 along a particular axis may refer to, e.g., a
change in a dimension of the haptic actuator 621 along that axis
(e.g., change in length, width, or thickness) relative to a
baseline state in which the haptic actuator 621 was not
activated.
In an embodiment, the displacement amplification device includes a
lever device that is configured to perform the conversion from the
first displacement to the second displacement. For instance, the
displacement conversion device 621b-1/621b-2 in FIGS. 8A-8C is a
lever device that includes a first disc 621b-1 and a second disc
621b-2 disposed on opposite sides or opposing surfaces of the layer
621a of piezoelectric material. Each disc of the first disc 621b-1
and second disc 621b-2 may be, e.g., a metal sheet (also referred
to as a metal layer) that tapers from a circular base portion
(e.g., 621f-1) to a circular central portion (e.g., 621g-1) to form
a truncated cone with a respective planar surface 621a-1/621a-2 of
the layer 621a of piezoelectric material. The truncated cone may
also be referred to as a cymbal or a truncated conical endcap. As
illustrated in FIG. 8B, the truncated cone may have a sloped
portion with a slope length S, wherein the sloped portion may form
an angle .theta. with a planar surface (e.g., 621a-1) of the layer
621a of piezoelectric material. In some cases, the angle .theta.
may have a value of less than 45.degree. (e.g., 15.degree.). The
sloped portion may create a height H for the truncated cone. The
height H may be equal to or substantially equal to a height of the
first disc 621b-1 and/or of the second disc 621b-2, and may be in a
range of, e.g., 0.2 mm to 0.7 mm. If the sloped portion were
projected onto the planar surface 621a-1, it may further have a
base width B. Further, each disc of the first disc 621b-1 and the
second disc 621b-2 may have a thickness T.sub.3 (see FIG. 8B) that
is a range of 0.1 mm to 0.5 mm. As depicted in FIG. 8A, the
circular base portion (e.g., 621f-1) of each of the discs 621b-1,
621-b2 may have a diameter d.sub.1 that is in a range of 9 mm to 12
mm, while the circular central portion (e.g., 621g-1) of each of
the discs 621b-1, 621b-2 may have a diameter d.sub.2 that is in a
range of 2 mm to 3 mm. The values of the dimensions discussed above
are only examples, and the various dimensions presented above may
have other values.
In an embodiment, the haptic actuator 621 may interface with other
components (e.g., with a pre-load device) via a surface of the
displacement conversion device 621b-1/621b-2. For instance, the
haptic actuator 621 may interface with the pre-load device via an
outer surface 621h-1 of a circular central portion (e.g., 261g-1)
of disc 621b-1, and/or with an outer surface 621h-2 of a circular
central portion (e.g., 261g-1) of disc 621b-2. The outer surface
621h-1 and the outer surface 621h-2 may form opposite outer
surfaces (also referred to as opposing outer surfaces) of the
haptic actuator 621, and may act as a first interface surface and a
second interface surface, respectively, for the haptic actuator
621. In such an embodiment, a pre-load device may include a first
component and a second component that are disposed on the
respective opposite surfaces of the haptic actuator 621. In some
cases, a layer of adhesive may be applied on the outer surfaces
621h-1, 621h-2 to adhere them to a first component and a second
component of a pre-load device.
In an embodiment, as illustrated in FIGS. 8B and 8C, the haptic
actuator 621 further includes electrodes 621c-1 and 621c-2. When a
voltage difference is created between the electrodes 621c-1 and
621c-2, the layer 621a of piezoelectric material may output strain
along the axis 618 and/or the axis 619. For instance, the layer
621a of piezoelectric material may contract along the axis 619 to a
contracted state CS indicated by the dashed lines in FIG. 8C. In an
embodiment, the layer 621a of piezoelectric material may also
experience some strain along the axis 617, but to a much lesser
degree than the strain along the axis 619. In an embodiment, the
displacement or deformation of the layer 621a along the axis 619
may be in a range of 5 .mu.m to 50 .mu.m, while the displacement or
deformation of the layer 621a along the axis 617 may be in a range
of 0.5 .mu.m to 2 .mu.m. In an embodiment, the layer 621a may also
generate strain along the axis 618. The strain along the axis 619
and the strain along the axis 618 may be the same, or may differ.
The displacement conversion device 621b-1/621b-2 in FIG. 8C may
convert the strain along the axis 619 to expansion of the haptic
actuator 621 along the axis 617 to an expanded state ES indicated
by the dashed lines in FIG. 8C. The displacement that is output by
the haptic actuator 621 may come from the expansion of the haptic
actuator 621.
FIG. 8D illustrates an embodiment of the layer 621a of
piezoelectric material that includes a stack of sub-layers 621p-1,
621p-2, 621p-3, 621p-4 . . . 621p-n of piezoelectric material.
Further, the electrode 621c-1 and the electrode 621c-2 may form an
inter-digitated or comb-like pattern. This pattern may reduce a
distance between the two electrodes, which may allow a stronger
electric field to be created between them. More specifically, the
electrode 621c-1 may include a first set of electrode layers
621d-1, 621d-2 . . . 621d-n that are embedded within the layer 621a
of piezoelectric material. Each electrode layer of the first set of
electrode layers 621d-1 . . . 621d-n may extend substantially
through a length or width of the layer 621a. Similarly, the
electrode 621c-2 may include a second set of electrode layers
621e-1, 621e-2 . . . 621e-n that are also embedded within the layer
621a of piezoelectric material. Each electrode layer of the second
set of electrode layers 621e-1 . . . 621e-n may extend
substantially through the length or width of the layer 621a.
In an embodiment, each sub-layer of the plurality of sub-layers
621p-1 . . . 621p-n may be disposed directly between one of the
first set of electrode layers 621d-1 . . . 621d-n and one of the
second set of electrode layers 621e-1 . . . 621e-n, such that the
two electrode layers are immediately adjacent to the sub-layer. For
instance, the sub-layer 621p-1 is disposed directly between the
electrode layer 621d-1 and the electrode layer 621e-1, wherein the
electrode layer 621d-1 and the electrode layer 621e-1 are
immediately adjacent to the sub-layer 621p-1.
In an embodiment, when a voltage difference is created between any
electrode layer of the first set of electrode layers 621d-1 . . .
621d-n and a corresponding or adjacent electrode layer of the
second set of electrode layers 621e-1 . . . 621e-n, the voltage
difference may generate an electric field between the two electrode
layers. The electric field may be aligned along the axis 617. In an
embodiment, the axis 617 may be parallel with a poling direction of
the piezoelectric material of each sub-layer of the plurality of
sub-layers 621p-1 . . . 621p-n. In an embodiment, the poling
direction of the piezoelectric material may be parallel with each
sub-layer of the plurality of sub-layers 621p-1 . . . 621p-n, or
more generally may be parallel with the layer 621a. For instance,
the poling direction may be parallel with a length dimension or a
width dimension of the layer 621a. The electric field along the
axis 617 between the two electrode layers may cause a sub-layer of
piezoelectric material between them to generate strain. The strain
may be along one or more of the axes 617-619. For instance, FIG. 8D
depicts the sub-layers 621p-1 . . . 621-n contracting along the
axis 619 and expanding along the axis 617, as indicated by the
dashed lines in the figure. The amount of strain along the axis 619
may be based on a value of a d.sub.31 coefficient of the
piezoelectric material, while the amount of strain along the axis
617 may be based on a value of a d.sub.33 coefficient of the
piezoelectric material. In an embodiment, the amount of strain
along the axis 619 may be considerably larger than the amount of
strain along the axis 617.
As stated above, the displacement conversion device 621b-1/621b-2
may be configured to convert the strain along the axis 619 to
displacement and force along the axis 617. In an embodiment, the
displacement conversion device 621b-1/621b-2 may form a plurality
of linkages that are connected by joints (e.g., living hinges), and
a geometry of the linkages may cause the strain along the axis 619
to be converted, and in some cases amplified, to displacement along
the axis 617. For instance, FIG. 8B depicts a geometry that
involves the dimensions S, H, and B, which are discussed above with
respect to FIG. 8B. These dimensions may correspond to dimensions
of a right triangle. As depicted in FIGS. 8B and 8C, when there is
strain along the axis 619, the layer 621a of piezoelectric material
may decrease in length or width, to the contracted state CS. As a
result, the dimension B may decrease, which may force the angle
.theta. to increase. The increase in .theta. may in turn increase
the dimension H. The dimension S may remain the same, such as at a
value of S.sub.1, as .theta. changes. In this situation, because
the dimensions of S (which equals S.sub.1), B, and H correspond to
those of a right triangle, the value of B may be calculated as
S.sub.1 cos .theta., while the value of H may be calculated as
S.sub.1 sin .theta.. FIG. 8E illustrates a plot of H and B for such
a situation, in which strain along the axis 619 of FIG. 8C causes a
change in B (i.e., .DELTA.B) and a change in H (i.e., .DELTA.H).
The quantity .DELTA.B may represent a displacement along the axis
619, while the quantity .DELTA.H may represent a displacement along
the axis 617. As depicted in FIGS. 8B, 8C, and 8E, a strain that
contracts the layer 621a to the contracted state CS may force the
angle .theta. to increase, from .theta..sub.1 to .theta..sub.2. In
FIG. 8E, both .theta..sub.1 to .theta..sub.2 are less than
45.degree.. In such an embodiment, the increase in .theta. may
result in a greater .DELTA.H relative to .DELTA.B. In other words,
FIG. 8E demonstrates that a geometry such as that in FIGS. 8B and
8C may result in displacement along the axis 617 being amplified
relative to displacement along the axis 619.
FIG. 9 depicts a haptic actuator 721 that is an embodiment of the
haptic actuator 521. Like the haptic actuator 621, the haptic
actuator 721 includes a layer 721a piezoelectric material. The
haptic actuator 721 further includes a displacement conversion
device 721b that is configured to generate strain along an axis 719
that is parallel to a planar surface 721a-1 of the layer 721a to
displacement along an axis 717. Axis 719 may be referred to as a
parallel axis, while axis 717 may be referred to as a perpendicular
axis. As depicted in FIG. 9, the displacement conversion device
721b may form a frame that includes a pair of linkages 721b-1,
721b-2 that each act as a lever to amplify displacement along the
axis 719 to a greater amount of displacement along the axis 717.
The pair of linkages 721b-1, 721b-2 may be connected to a center
portion 721b-3 by a pair of respective living hinges 721c-1,
721c-2. The frame may also include a pair of linkages 721b-5,
721b-6 that also act as levers to amplify displacement along the
axis 719 to a greater amount of displacement along the axis 717.
The pair of linkages 721b-5, 721b-6 may be connected to a center
portion 721b-4 by another pair of respective living hinges 721c-3,
721c-4. The center portions 721b-3 and 721b-4 may, e.g., act as
respective interface surfaces for the haptic actuator 721, and may
in some cases act as respective opposing outer surfaces of the
haptic actuator 721. Displacement conversion and amplification
devices are also discussed in U.S. Pat. No. 9,866,149 (IMM539),
entitled "Method and Apparatus for Enabling Floating Touch Screen
Haptics Assemblies," the entire content of which is incorporated
herein by reference.
FIG. 10 depicts a partially exploded view of a haptic actuator
assembly 820 that is an embodiment of any of the haptic actuator
assemblies 120 through 520. The haptic actuator assembly includes a
haptic actuator 821 and a pre-load device 827. In an embodiment,
the haptic actuator 821 may be similar to the haptic actuator 621,
and may include a layer 821a of piezoelectric material that is
configured to generate strain along an axis 819 that is parallel to
a planar surface 821a-1 of the layer 821a. The haptic actuator
assembly 820 further includes a displacement conversion device that
includes a first disc 821b-1 and a second disc 821b-2. Similar to
the displacement conversion device 621b-1/621b-2, each of the first
disc 821b-1 and the second disc 821b-2 may be a metal layer that
forms a truncated cone (also referred to as a cymbal) with a
respective surface of the layer 821a of piezoelectric material. In
an embodiment, the pre-load device 827 includes a first component
827a and a second component 827b that are configured to generate a
pre-load in the form of a compressive load that opposes expansion
of the haptic actuator 821 along an axis 817 that is perpendicular
to or substantially perpendicular to the planar surface 821a-1 of
the layer 821a, and thus opposes expansion of the haptic actuator
assembly 820 along the axis 817 (axis 819 may be referred to as a
parallel axis, while axis 817 may be referred to as a perpendicular
axis).
In an embodiment, the first component 827a and the second component
827b may be configured to generate a pre-load through one or more
spring components disposed between the first component 527a and the
second component 527b in order to create the compressive load. In
an embodiment, the first component 827a and the second component
827b may be configured to generate a pre-load, in the form of a
compressive load on the haptic actuator 821, which is in a range of
2 N to 4 N. The pre-load in a range of 2N to 4 N enables the haptic
actuator 821 to reliably and predictably deform in response to an
applied electrical potential. The haptic actuator 821 may break
upon application of an electrical potential if it is not
sufficiently pre-loaded, while conversely the haptic actuator may
not be able to reliably and predictably deform if it is excessively
pre-loaded.
FIGS. 11 and 12 illustrate an embodiment in which the pre-load, or
more specifically a compressive load, is created by a spring
component 1160. More specifically, FIGS. 11 and 12 illustrate
perspective and sectional side views, respectively, of a haptic
actuator assembly 1120 that includes the haptic actuator 621
previously described above as well as a pre-load device 1127.
Although the haptic actuator assembly 1120 is shown and described
with the haptic actuator 621, any haptic actuator described herein
may also be utilized with the pre-load device 1127. The pre-load
device 1127 is configured to create a compressive load on the
haptic actuator 621 along the axis 617, and the compressive load
opposes expansion, or more generally deformation, of the haptic
actuator 621 along the axis 617.
The pre-load device 1127 includes the spring component 1160 and a
casing 1162. In an embodiment, the casing 1162 includes a cover
1164 and a base 1166 that opposes the cover 1164. In an embodiment,
the cover 1164 is spaced apart from but extends generally parallel
to the base 1166. In an embodiment, the casing 1162 may be formed
from a material that is light weight yet strong, such as
acrylonitrile butadiene styrene (ABS), polycarbonate,
polypropylene, polyurethane or other polymeric material. The cover
1164 and the base 1166 may be planar components that have the same
size and shape (e.g., rectangular or circular shape), or may have
different sizes and/or shapes. In some instances, the cover 1164
and the base 1166 may each be rectangular, and may each have a
length and a width that are each in a range of 9 mm to 25 mm. In an
embodiment, the cover 1164 and the base 1166 each have a thin
profile in order to keep a low overall thickness for the haptic
actuator assembly 1120. For instance, the cover 1164 and the base
1166 may each have a thickness that is in a range of 1 mm to 2 mm.
In an embodiment, the casing 1162 may have an overall thickness
that is in a range of 1 mm to 5 mm.
The casing 1162 holds or retains the spring component 1160 and the
haptic actuator 621, including both the layer 621a of piezoelectric
material and the displacement conversion device 621b-1/621b-2. The
haptic actuator 621 is disposed within the casing 1162 between the
cover 1164 and the base 1166, with the cover 1164 and the base 1166
being disposed at respective opposite ends of the haptic actuator
621 along the axis 617 thereof. In the embodiment of FIGS. 11 and
12, the base 1166 supports the haptic actuator 621, or stated
another way the haptic actuator 621 is disposed on an interior
surface of the base 1166. In an embodiment, the base 1166 may be
attached to the haptic actuator 621 via an adhesive or some other
manner of attachment.
In addition to the pre-load functions described in more detail
herein, the casing 1162 functions to provide the haptic actuator
assembly 1120 as a self-contained device in which the pre-load
generated thereby is a load that is, e.g., built into the haptic
actuator assembly 1120 or internal to the haptic actuator assembly
1120. As such, the pre-load generated by the pre-load device 1127
may be a load that is independent of user interaction or influences
that are external to the haptic actuator assembly 1120. For
example, the haptic actuator assembly 1120 having the pre-load
device 1127 may be disposed at a location at which the haptic
actuator assembly 1120 will experience little to no external load.
For instance, the haptic actuator assembly 1120 may be disposed at
a back side of a mobile phone, such as on an inner surface of a
back panel of the mobile phone as described above with respect to
FIG. 3B. The back panel may have a low mass, and may exert less
than 1 N of external load on the haptic actuator assembly 1120.
In an embodiment, the casing 1162 may include one or more sidewalls
(not shown) extending between the cover 1164 and the base 1166. In
an embodiment, the sidewalls permit movement between the cover 1164
and the base 1166 and therefore function similar to a suspension
system that is configured to allow preferential movement of the
cover 1164 and/or the base 1166 along a certain axis, such as along
the perpendicular axis 617. In another embodiment, the casing 1162
may include one or more partial sidewalls (not shown) that do not
extend the full length between the cover 1164 and the base 1166.
The partial sidewalls may, for example, extend from the cover 1164
towards the base 1166 or may extend from the base 1166 towards the
cover 1164. In yet another embodiment, the casing 1162 may include
one or more one or more connectors or columns extending between the
cover 1164 and the base 1166. Sidewalls, partial sidewalls, and/or
connectors/columns of the casing 1162 may assist in forming the
haptic actuator assembly 1120 as a self-contained device.
The spring component 1160 is disposed within the casing 1162 such
that a first end 1161A is coupled to an interior surface of the
cover 1164 and a second opposing end 1161B is coupled to an outer
surface of the haptic actuator 621. The spring component 1160 is
configured to create a compressive load on the haptic actuator 621
along the axis 617, and the compressive load opposes expansion of
the haptic actuator 621 along the axis 617. The spring component
1160 is shown as a helical element for illustrative purposes only
to represent the functional operation of the spring component 1160
and is not intended to limit an actual physical shape thereof. The
spring component 1160 may be any type of spring element having the
spring properties to exert the desired compressive force, including
but not limited to elastomers, helical or coiled springs, leaf
springs, flat springs, wave washers, snap dome springs, or a
compliant element such as rubber, foam, or flexures. For example,
FIG. 14 depicts a haptic actuator assembly 1420 including a spring
component 1460 that is an embodiment of the spring component 1160.
In FIG. 14, the spring component 1460 is a spring plunger or other
spring-loaded device that increases the spring force of a spring by
encapsulating it in a body 1467 and providing a plunger tip or ball
1469 on one end to enable accurate and repeatable end force. As
another example, FIG. 15 depicts a haptic actuator assembly 1520
including a spring component 1560 that is an embodiment of the
spring component 1160. In FIG. 15, the spring component 1560
includes a screw 1570 and a flexible film component 1572 that has
the spring properties to exert the desired compressive force. The
screw 1570 may be used to adjust a spring force of the flexible
film component 1572. More particularly, as the screw 1570 is
further advanced onto the flexible film component 1572, the spring
force exerted by the flexible film component 1572 onto the haptic
actuator 621 is further increased. Conversely, if it is desired to
decrease the amount of spring force exerted onto the haptic
actuator 621 by the flexible film component 1572, the screw 1570
may be retracted. Although there is a single spring component
illustrated in each of FIGS. 11 and 12, it should be understood
that in some implementations, multiple spring components may be
used in the haptic actuator assembly 1120 to exert the desired
compressive force.
To generate a pre-load, the cover 1164 urges the spring component
1160 against the haptic actuator 621 to apply a compressive force
against haptic actuator 621. In an embodiment, the spring component
1160 may be configured to generate a pre-load that is in a range of
2 N to 4 N. The pre-load in a range of 2 N to 4 N enables the
haptic actuator 621 to reliably and predictably deform in response
to an applied electrical potential. When the haptic actuator 621
deforms in response to an applied electrical potential, the spring
component 1160 exerts a spring force on the haptic actuator 621
that constrains the displacement from the haptic actuator 621 to a
value that is a fraction (e.g., 1/2, 3/4) of its rated
displacement. By decreasing the displacement output from the haptic
actuator 621, the spring component 1160 causes an increase in the
force output by the haptic actuator 621. As a result, when a
vibrotactile haptic effect is generated by the haptic actuator
assembly 1120, the force accompanying the vibrotactile haptic
effect may be stronger and more perceivable relative to the
situation in which the vibrotactile haptic effect is generated by a
haptic actuator having no pre-load.
FIG. 11 further illustrates a power source 1140 that may provide
power to the haptic actuator assembly 1120. The power source 1140
is an embodiment of the power source 140 described above. In an
embodiment, electrical leads electrically connect the power source
1140 to electrodes 621c-1/621c-2 of the haptic actuator 621. The
power source 1140 may be controlled by a control unit 1130 to
provide a drive signal, such as a voltage signal or a drive signal,
to electrodes 621c-1/621c-2 of the haptic actuator 621. The control
unit 1130 is an embodiment of the control unit 130 described above.
In an embodiment, the control unit 1130 may control the power
source 1140 to provide a sinusoidal drive signal to the haptic
actuator assembly 1120, which may cause the haptic actuator 621 to
output an oscillating displacement, such as a vibration, along the
axis 617. In an embodiment, the sinusoidal drive signal may have a
peak-to-peak amplitude that is in a range of, e.g., 60 V to 120 V,
and a frequency that is in a range of 50 Hz to 200 Hz. The pre-load
device 1127 may generate a compressive load that is in a range of,
e.g., 2 N to 4 N to oppose expansion, or more generally
displacement, by the haptic actuator 621 along the axis 617. As
described above, by decreasing the displacement output from the
haptic actuator 621, the pre-load device 1127 causes an increase in
the force output by the haptic actuator 621 and thereby causes or
creates a more perceivable haptic effect. The voltage signal or
drive signal may be adjusted by varying the applied voltage or
current, thereby controlling the force applied by the haptic
actuator assembly 1120.
In an embodiment, the haptic actuator assembly 1120 can function as
a harmonic oscillator that runs at a relatively high frequency. In
operation, when the power source 1140 provides a sinusoidal drive
signal to the haptic actuator assembly 1120, the haptic actuator
621 vibrates as directed by the oscillating drive signal. More
particularly, as described above with respect to the operation of
the haptic actuator 621, the displacement that is output by the
haptic actuator 621 along the axis 617 may come from the expansion
or contraction of the haptic actuator 621. In an embodiment,
displacement of the haptic actuator 621 along the axis 617 causes
movement or vibration of both the cover 1164 and the base 1166. In
another embodiment, one of the cover 1164 or the base 1166 is
configured to act as a mechanical ground as described in more
detail below such that displacement of the haptic actuator 621
along the axis 617 causes movement or vibration of only the other
opposing structure that is not configured to be a mechanical
ground. The haptic actuator assembly 1120 thus vibrates and
provides haptic sensations to the housing or part of the
haptic-enabled device to which it is attached.
As stated above, in an embodiment hereof, one of the cover 1164 or
the base 1166 may be configured to act as a mechanical ground while
the other structure vibrates/displaces. For example, in the
embodiment of FIG. 11, the cover 1164 which is attached to the
spring component 1160 may be configured to act as a mechanical
ground via the spring properties of the spring component 1160. When
spring component 1160 is selected to be sufficiently stiff, the
cover 1164 acts as a mechanical ground and thereby translate the
force generated by the haptic actuator 621 to the base 1166. Stated
another way, the mechanical ground functions to essentially channel
displacement from the haptic actuator assembly 1120 toward the base
1166 rather than the cover 1164. The spring component 1160 may be
incompressible along the axis 617, such that when the haptic
actuator 621 expands along the axis 617, the base 1164 provides
much less resistance against that expansion than does the spring
component 1160. As a result, most or all of the expansion of the
haptic actuator 621 may be channeled toward vibrating or displacing
the base 1166, rather than toward the cover 1164.
Alternatively, in another embodiment, the base 1166 may be
configured to act as a mechanical ground and thereby translate the
force generated by the haptic actuator 621 to the spring component
1160 and the cover 1164. The spring component 1160 may be
compressible along the axis 617, such that when the haptic actuator
621 expands along the axis 617, the spring component 1160 and the
cover 1164 provide much less resistance against that expansion than
does the base 1164. As a result, most or all of the expansion of
the haptic actuator 621 may be channeled toward vibrating or
displacing the cover 1164, rather than toward the base 1166. The
base 1166 may be of a relatively stiffer material having a suitable
Young's modulus and/or thickness to be configured to act as a
mechanical ground.
In an embodiment, the components of the haptic actuator assembly
1120 can be chosen to provide more effective haptic sensations and
the resonant frequency of the haptic actuator assembly 1120 is
tailored via the spring component 1160. The haptic actuator 621 has
a first resonant frequency and the haptic actuator assembly 1120
has a second resonant frequency, the second resonant frequency
being different than the first resonant frequency. The second
resonant frequency is a function of or is determined via a spring
constant of the first spring component 1160. For example, if the
haptic actuator 621 oscillates at a natural frequency of the haptic
actuator assembly 1120 (including the haptic actuator 621 as well
as the pre-load device 1127), then stronger forces and more
effective haptic sensations can be output. More particularly, when
the power source 1140 provides a drive signal to the haptic
actuator assembly 1120 and the drive signal is a periodic signal
having a frequency equal to a resonant frequency of the haptic
actuator assembly 1120, the haptic actuator assembly 1120 resonates
to provide more effective haptic sensations. Due to the addition of
the spring component 1160, the total spring constant of the haptic
actuator assembly 1120 is different than the spring constant of the
haptic actuator 621 alone. As such, the resonant frequency of the
haptic actuator assembly 1120 varies depending on the spring
constant of the spring component 1160 and the resonant frequency of
the haptic actuator assembly 1120 may be controlled by selecting a
particular or predetermined spring component 1160. Stated another
way, the spring component 1160 may be chosen to change or alter the
resonant frequency of the haptic actuator 621 alone such that the
haptic actuator assembly 1120 has a desired or predetermined
resonant frequency in order to amplify the output force and
effects. By controlling the resonant frequency, the haptic actuator
assembly 1120 may be configured to resonate at a certain frequency
to present a wide spectrum of frequencies by amplitude modulation
techniques. The haptic actuator assembly 1120 thus may be
configured to realize mechanical resonance as described above when
the drive signal has a frequency equal to a resonant frequency of
the haptic actuator assembly 1120.
In addition to tuning or tailoring the resonant frequency of the
haptic actuator assembly 1120 via the spring component 1160,
additional mass may be included on the base 1166 (or the cover 1164
if the base 1166 is configured to be the mechanical base and the
cover 1164 is configured to resonate) to ensure that the base 1166
has sufficient acceleration in the resonant frequency. Additional
mass may be included on the base 1166 by attaching a separate
component of a predetermined mass to the base 1166, or by forming
the base 1166 to have the predetermined mass.
FIG. 13 illustrates an embodiment in which the pre-load, or more
specifically a compressive load, is created by a first spring
component 1360A and a second spring component 1360B. More
specifically, FIG. 13 illustrates a sectional side view of a haptic
actuator assembly 1320 that includes the haptic actuator 621
previously described above as well as a pre-load device 1327.
Although the haptic actuator assembly 1320 is shown and described
with the haptic actuator 621, any haptic actuator described herein
may also be utilized with the pre-load device 1327. The pre-load
device 1327 is configured to create a compressive load on the
haptic actuator 621 along the axis 617, and the compressive load
opposes expansion, or more generally deformation, of the haptic
actuator 621 along the axis 617.
The pre-load device 1327 includes the first spring component 1360A,
the second spring component 1360B and a casing 1362. The casing
1362 is similar to the casing 1162 described above and includes a
cover 1364 and a base 1366 spaced apart from and extending parallel
to the cover 1364. The casing 1362 holds or retains the first
spring component 1360A, the second spring component 1360B, and the
haptic actuator 621, including both the layer 621a of piezoelectric
material and the displacement conversion device 621b-1/621b-2. The
haptic actuator 621 is disposed between the cover 1364 and the base
1366, with the cover 1364 and the base 1366 being disposed at
respective opposite ends of the haptic actuator 621 along the axis
617. In this embodiment, however, the haptic actuator 621 does not
contact the cover 1364 or the base 1366 but rather is suspended
between the cover 1364 and the base 1366 via the first spring
component 1360A and the second spring component 1360B as will be
described in more detail below.
As described above with respect to casing 1162, the casing 1362
functions to provide the haptic actuator assembly 1320 as a
self-contained device in which the pre-load generated thereby is a
load that is, e.g., built into the haptic actuator assembly 1320 or
internal to the haptic actuator assembly 1320. As such, the
pre-load generated by the pre-load device 1327 may be a load that
is independent of user interaction or influences that are external
to the haptic actuator assembly 1320. For example, the haptic
actuator assembly 1320 having the pre-load device 1327 may be
disposed at a location at which the haptic actuator assembly 1320
will experience little to no external load. For instance, the
haptic actuator assembly 1320 may be disposed at a back side of a
mobile phone, such as on an inner surface of a back panel of the
mobile phone as described above with respect to FIG. 3B. The back
panel may have a low mass, and may exert less than 1 N of external
load on the haptic actuator assembly 1120.
More particularly, the first spring component 1360A is disposed
within the casing 1362 such that a first end 1361A is coupled to an
interior surface of the cover 1364 and a second opposing end 1361B
is coupled to an outer surface of the haptic actuator 621. The
second spring component 1360B is disposed within the casing 1362
such that a first end 1361C is coupled to an interior surface of
the base 1366 and a second opposing end 1361D is coupled to an
outer surface of the haptic actuator. Collectively, the first
spring component 1360A and the second spring component 1360B are
configured to create a compressive load on the haptic actuator 621
along the axis 617, and the compressive load opposes expansion of
the haptic actuator 621 along the axis 617. The first spring
component 1360A and the second spring component 1360B are shown as
helical elements for illustrative purposes only to represent the
functional operation thereof and the depiction is not intended to
describe or limit an actual physical shape thereof. The first
spring component 1360A and the second spring component 1360B may be
any type of spring element having the spring properties to exert
the desired compressive force, including but not limited to
elastomers, helical or coiled springs, leaf springs, flat springs,
wave washers, snap dome springs, or a compliant element such as
rubber, foam, or flexures. Further, although there is a single
spring element illustrated in FIG. 13 for each of the first spring
component 1360A and the second spring component 1360B, it should be
understood that in some implementations, multiple spring components
may be used for each of the first spring component 1360A and the
second spring component 1360B to exert the desired compressive
force.
To generate a pre-load, the cover 1364 urges the first spring
component 1360A against the haptic actuator 621 while the base 1366
urges the second spring component 1360B against the haptic actuator
621 to collectively apply a compressive force against haptic
actuator 621. In an embodiment, first spring component 1360A and
the second spring component 1360B may be configured to collectively
generate a pre-load that is in a range of 2 N to 4 N. The pre-load
in a range of 2 N to 4 N enables the haptic actuator 621 to
reliably and predictably deform in response to an applied
electrical potential. When the haptic actuator 621 deforms in
response to an applied electrical potential, the first spring
component 1360A and the second spring component 1360B each exert a
spring force on the haptic actuator 621 that constrains the
displacement from the haptic actuator 621 to a value that is a
fraction (e.g., 1/2, 3/4) of its rated displacement. By decreasing
the displacement output from the haptic actuator 621, the first
spring component 1360A and the second spring component 1360B
collectively cause an increase in the force output by the haptic
actuator 621. As a result, when a vibrotactile haptic effect is
generated by the haptic actuator assembly 1320, the force
accompanying the vibrotactile haptic effect may be stronger and
more perceivable relative to the situation in which the
vibrotactile haptic effect is generated by a haptic actuator having
no pre-load.
Similar to the haptic actuator assembly 1120, the haptic actuator
assembly 1320 can function as a harmonic oscillator that runs at a
relatively high frequency and operates similar to the haptic
actuator assembly 1120. In operation, when a power source (not
shown in FIG. 13) provides a sinusoidal drive signal to the haptic
actuator assembly 1320, the haptic actuator 621 vibrates as
directed by the oscillating drive signal. More particularly, as
described above with respect to the operation of the haptic
actuator 621, the displacement that is output by the haptic
actuator 621 along the axis 617 may come from the expansion or
contraction of the haptic actuator 621. In an embodiment,
displacement of the haptic actuator 621 along the axis 617 causes
movement or vibration of both the cover 1364 and the base 1366. In
another embodiment, one of the cover 1364 or the base 1366 is
configured to act as a mechanical ground as described in more
detail below such that displacement of the haptic actuator 621
along the axis 617 causes movement or vibration of only the other
opposing structure that is not configured to be a mechanical
ground. The haptic actuator assembly 1320 thus vibrates and
provides haptic sensations to the housing or part of the
haptic-enabled device to which it is attached.
As stated above, in an embodiment hereof, one of the cover 1364 or
the base 1366 may be configured to act as a mechanical ground while
the other structure vibrates/displaces. For example, in the
embodiment of FIG. 13, the cover 1364 which is attached to the
first spring component 1360A may be configured to act as a
mechanical ground via the spring properties of the first spring
component 1360A. When first spring component 1360A is selected to
be sufficiently stiff, the cover 1364 acts as a mechanical ground
and thereby translate the force generated by the haptic actuator
621 to the second spring component 1360A (which is compressible
along the axis 617) and the base 1366 attached thereto. Stated
another way, the mechanical ground functions to essentially channel
displacement from the haptic actuator assembly 1320 toward the base
1366 rather than the cover 1364. The first spring component 1360A
may be incompressible along the axis 617, such that when the haptic
actuator 621 expands along the axis 617, the second spring
component 1360A and the base 1366 attached thereto provides much
less resistance against that expansion than does the first spring
component 1360. As a result, most or all of the expansion of the
haptic actuator 621 may be channeled toward vibrating or displacing
the base 1366, rather than toward the cover 1364. In another
embodiment hereof, the base 1366 which is attached to the second
spring component 1360B may be configured to act as a mechanical
ground via the spring properties of the second spring component
1360B.
In an embodiment, the components of the haptic actuator assembly
1320 can be chosen to provide more effective haptic sensations.
More particularly, the spring constants of the first spring
component 1360A and the second spring component 1360B may be
different from each other. For example, as described above, the
spring constants of the first spring component 1360A and the second
spring component 1360B may be different from each other and may be
configured such that one of the cover 1364 or the base 1366 is
configured to act as a mechanical ground and displacement of the
haptic actuator 621 along the axis 617 causes movement or vibration
of only the other opposing structure that is not configured to be a
mechanical ground. When the haptic actuator assembly 1320 is
disposed underneath of a touchscreen of a mobile device, for
example, such differential spring constants that provide a
mechanical ground via the second spring component 1360B while
permitting movement or vibration via the first spring component
1360A will essentially suspend the touchscreen and permit the
haptic effects to be felt by the user.
In addition, in an embodiment, the spring constants of the first
spring component 1360A and the second spring component 1360B may be
different from each other and may be configured such that the
haptic actuator assembly 1320 is configured to realize mechanical
resonance. Stated another way, the resonant frequency of the haptic
actuator assembly 1320 is tailored via the first spring component
1360A and the second spring component 1360B. The haptic actuator
621 has a first resonant frequency and the haptic actuator assembly
1320 has a second resonant frequency, the second resonant frequency
being different than the first resonant frequency. The second
resonant frequency is a function of or is determined via the spring
constants of the first spring component 1360A and the second spring
component 1360B. Due to the addition of the first spring component
1360A and the second spring component 1360B, the total spring
constant of the haptic actuator assembly 1320 is different than the
spring constant of the haptic actuator 621 alone. As such, the
resonant frequency of the haptic actuator assembly 1320 varies
depending on the spring constants of each of the first spring
component 1360A and the second spring component 1360B and the
resonant frequency of the haptic actuator assembly 1320 may be
controlled by selecting particular or predetermined spring
components 1360A, 1360B. Stated another way, the first spring
component 1360A and the second spring component 1360B may be chosen
to change or alter the resonant frequency of the haptic actuator
621 alone such that the haptic actuator assembly 1320 has a desired
or predetermined resonant frequency in order to amplify the output
force and effects. By controlling the resonant frequency, the
haptic actuator assembly 1320 may be configured to resonate at a
certain frequency to present a wide spectrum of frequencies by
amplitude modulation techniques. Utilizing two spring components in
the haptic actuator assembly 1320 (i.e., the first spring component
1360A and the second spring component 1360B) allows for a wide
range of possibilities for tailoring the resonant frequency of the
haptic actuator assembly 1320 since two spring components
contribute to the overall stiffness of the system. Stated another
way, the resonant frequency of the system is a function of the
overall stiffness of the system, which can be tuned or tailored by
various combinations of spring constants of the first spring
component 1360A and the second spring component 1360B.
In addition to tuning or tailoring the resonant frequency of the
haptic actuator assembly 1320 via the first spring component 1360A
and the second spring component 1360B, additional mass may be
included on the base 1366 (or the cover 1364 if the base 1366 is
configured to be the mechanical base and the cover 1364 is
configured to resonate) to ensure that the base 1366 has sufficient
acceleration in the resonant frequency. Additional mass may be
included on the base 1366 by attaching a separate component of a
predetermined mass to the base 1366, or by forming the base 1366 to
have the predetermined mass.
FIGS. 16A and 16B illustrates an embodiment in which the pre-load,
or more specifically a compressive load, is created by a casing
1662 that includes a first spring component 1660A and a second
spring component 1660B that releasably couple elements of the
casing 1662 together. More specifically, FIG. 16B illustrates a
sectional side view of a haptic actuator assembly 1620 that
includes the haptic actuator 621 previously described above as well
as a pre-load device 1627. Although the haptic actuator assembly
1620 is shown and described with the haptic actuator 621, any
haptic actuator described herein may also be utilized with the
pre-load device 1627. The pre-load device 1627 is configured to
create a compressive load on the haptic actuator 621 along the axis
617, and the compressive load opposes expansion, or more generally
deformation, of the haptic actuator 621 along the axis 617.
The pre-load device 1627 includes the first spring component 1660A,
the second spring component 1660B and the casing 1662. The casing
1662 includes a cover 1664 and a base 1666 spaced apart from and
extending parallel to the cover 1664. In an embodiment, the base
1666 includes a sidewall 1668 that is disposed around a perimeter
of the base 1666 and extends in a direction towards the cover 1664.
The sidewall 1668 does not extend between the base 1666 and the
cover 1664, and does not directly contact the cover 1664. The
sidewall 1668 defines an end surface 1674. The first spring
component 1660A and the second spring component 1660B are each
attached to and extend outwardly from a respective outer end 1676
of the cover 1664, as best shown in FIG. 16A which is a side view
of the cover 1664 prior to assembly into the casing 1662. The first
spring component 1660A and the second spring component 1660B are
disposed at opposing ends of the casing 1662. When the cover 1664
is assembled onto the base 1666, as shown in FIG. 16B, the first
spring component 1660A and the second spring component 1660B are
each releasably attached to the base 1666. More particularly, the
first spring component 1660A extends between the outer end 1676 of
the cover 1664 and the end surface 1674 of the sidewall 1668, and
the second spring component 1660B extends between the outer end
1676 of the cover 1664 and the end surface 1674 of the sidewall
1668.
After the cover 1664 and the base 1666 are assembled such that they
are coupled together via the first spring component 1660A and the
second spring component 1660B, the casing 1662 is configured to
hold or contain the haptic actuator 621, including both the layer
621a of piezoelectric material and the displacement conversion
device 621b-1/621b-2. The haptic actuator 621 is disposed between
the cover 1664 and the base 1666, with the cover 1664 and the base
1666 being disposed at respective opposite ends of the haptic
actuator 621 along the axis 617 thereof. In an embodiment, the base
1666 supports the haptic actuator 621, or stated another way the
haptic actuator 621 is disposed on an interior surface of the base
1166. In an embodiment, the base 1666 may be attached to the haptic
actuator 621 via an adhesive or some other manner of
attachment.
As described above with respect to casing 1162, the casing 1662
functions to provide the haptic actuator assembly 1620 as a
self-contained device in which the pre-load generated thereby is a
load that is, e.g., built into the haptic actuator assembly 1620 or
internal to the haptic actuator assembly 1620. As such, the
pre-load generated by the pre-load device 1627 may be a load that
is independent of user interaction or influences that are external
to the haptic actuator assembly 1620. For example, the haptic
actuator assembly 1620 having the pre-load device 1627 may be
disposed at a location at which the haptic actuator assembly 1620
will experience little to no external load. For instance, the
haptic actuator assembly 1620 may be disposed at a back side of a
mobile phone, such as on an inner surface of a back panel of the
mobile phone as described above with respect to FIG. 3B. The back
panel may have a low mass, and may exert less than 1 N of external
load on the haptic actuator assembly 1120. The sidewalls 1668 of
the base 1666 assist in the above-described functions of the casing
1662. However, in an embodiment, one or more of the sidewalls 1668
may be omitted. Further, the first spring component 1660A and/or
the second spring component 1660B may extend between the cover 1664
and the base 1666 if the spring component is disposed at a location
in which a sidewall has been omitted. In addition, the sidewalls
1668 are not required to extend the entire length or width of the
cover 1664 and/or the base 1666. For example, in an embodiment,
each sidewall 1668 may have a column configuration and be disposed,
e.g., between the corners of the cover 1664 and the base 1666.
Collectively, the first spring component 1660A and the second
spring component 1660B are configured to create a compressive load
on the haptic actuator 621 along the axis 617, and the compressive
load opposes expansion of the haptic actuator 621 along the axis
617. The first spring component 1660A and the second spring
component 1660B may be any type of spring element having the spring
properties to exert the desired compressive force, including but
not limited to elastomers, helical or coiled springs, leaf springs,
flat springs, wave washers, snap dome springs, or a compliant
element such as rubber, foam, or flexures. Further, although there
is a single spring element illustrated in FIG. 16 for each of the
first spring component 1660A and the second spring component 1660B,
it should be understood that in some implementations, multiple
spring components may be used for each of the first spring
component 1660A and the second spring component 1660B to exert the
desired compressive force.
To generate a pre-load, the first spring component 1660A and the
second spring component 1660B each provide a pulling spring force
to urge the cover 1664 and the base 1666 against the haptic
actuator 621. Stated another way, the first spring component 1660A
and the second spring component 1660B may each be considered to be
a tensioner that applies a force to urge the cover 1664 and the
base 1666 towards each other. In turn, the cover 1664 and the base
1666 thereby exert the desired compressive force against the haptic
actuator 621 to generate the pre-load. In an embodiment, first
spring component 1660A and the second spring component 1660B may be
configured to collectively generate a pre-load that is in a range
of 2 N to 4 N. The pre-load in a range of 2 N to 4 N enables the
haptic actuator 621 to reliably and predictably deform in response
to an applied electrical potential. When the haptic actuator 621
deforms in response to an applied electrical potential, the
pre-load exerted on the haptic actuator 621 constrains the
displacement from the haptic actuator 621 to a value that is a
fraction (e.g., 1/2, 3/4) of its rated displacement. By decreasing
the displacement output from the haptic actuator 621, the first
spring component 1660A and the second spring component 1660B are
configured to collectively cause an increase in the force output by
the haptic actuator 621. As a result, when a vibrotactile haptic
effect is generated by the haptic actuator assembly 1620, the force
accompanying the vibrotactile haptic effect may be stronger and
more perceivable relative to the situation in which the
vibrotactile haptic effect is generated by a haptic actuator having
no pre-load.
Similar to the haptic actuator assembly 1120, the haptic actuator
assembly 1620 can function as a harmonic oscillator that runs at a
relatively high frequency and operates similar to the haptic
actuator assembly 1120. In operation, when a power source (not
shown in FIG. 16) provides a sinusoidal drive signal to the haptic
actuator assembly 1620, the haptic actuator 621 vibrates as
directed by the oscillating drive signal. More particularly, as
described above with respect to the operation of the haptic
actuator 621, the displacement that is output by the haptic
actuator 621 along the axis 617 may come from the expansion or
contraction of the haptic actuator 621. In an embodiment,
displacement of the haptic actuator 621 along the axis 617 causes
movement or vibration of both the cover 1664 and the base 1666. In
another embodiment, one of the cover 1664 or the base 1666 is
configured to act as a mechanical ground as described in more
detail below such that displacement of the haptic actuator 621
along the axis 617 causes movement or vibration of only the other
opposing structure that is not configured to be a mechanical
ground. The haptic actuator assembly 1620 thus vibrates and
provides haptic sensations to the housing or part of the
haptic-enabled device to which it is attached.
As stated above, in an embodiment hereof, one of the cover 1664 or
the base 1666 may be configured to act as a mechanical ground while
the other structure vibrates/displaces. For example, one of the
cover 1664 or the base 1666 may be of a relatively stiffer material
having a suitable Young's modulus and/or thickness to be configured
to act as a mechanical ground. The mechanical ground (i.e., one of
the cover 1664 or the base 1666) translates the force generated by
the haptic actuator 621 to the other planar element (i.e., the
other of the cover 1664 or the base 1666). Stated another way, the
mechanical ground functions to essentially channel displacement
from the haptic actuator assembly 1620 toward the other planar
element. As a result, most or all of the expansion of the haptic
actuator 621 may be channeled toward vibrating or displacing the
other planar element.
In an embodiment, the components of the haptic actuator assembly
1620 can be chosen to provide more effective haptic sensations.
More particularly, the spring constants of first spring component
1660A and the second spring component 1660B may be selected to tune
the respective spring component and tailor the haptic effects
accordingly. For example, in an embodiment, the haptic actuator
assembly 1620 may be configured to realize mechanical resonance.
Stated another way, the resonant frequency of the haptic actuator
assembly 1620 is tailored via the first spring component 1660A and
the second spring component 1660B. The haptic actuator 621 has a
first resonant frequency and the haptic actuator assembly 1620 has
a second resonant frequency, the second resonant frequency being
different than the first resonant frequency. The second resonant
frequency is a function of or is determined via the spring
constants of the first spring component 1660A and the second spring
component 1660B. Due to the addition of the first spring component
1660A and the second spring component 1660B, the total spring
constant of the haptic actuator assembly 1620 is different than the
spring constant of the haptic actuator 621 alone. As such, the
resonant frequency of the haptic actuator assembly 1620 varies
depending on the spring constants of each of the first spring
component 1660A and the second spring component 1660B and the
resonant frequency of the haptic actuator assembly 1620 may be
controlled by selecting particular or predetermined spring
components 1660A, 1660B. Stated another way, the first spring
component 1660A and the second spring component 1660B may be chosen
to change or alter the resonant frequency of the haptic actuator
621 alone such that the haptic actuator assembly 1620 has a desired
or predetermined resonant frequency in order to amplify the output
force and effects. By controlling the resonant frequency, the
haptic actuator assembly 1620 may be configured to resonate at a
certain frequency to present a wide spectrum of frequencies by
amplitude modulation techniques.
In addition to tuning or tailoring the resonant frequency of the
haptic actuator assembly 1620 via the first spring component 1660A
and the second spring component 1660B, additional mass may be
included on the moving planar element (i.e., one of the cover 1664
or the base 1664, which is not configured to be the mechanical
ground) to ensure that the moving planar element has sufficient
acceleration in the resonant frequency. Additional mass may be
included on the moving planar element by attaching a separate
component of a predetermined mass, or by forming the moving planar
element to have the predetermined mass.
In an embodiment, the spring constants of the first spring
component 1660A and the second spring component 1660B may be
different from each other. More particularly, when the first spring
component 1660A and the second spring component 1660B have
different spring constants and the haptic actuator 621 expands or
otherwise generates displacement along the axis 617, the
displacement of the base 1666 and/or the cover 1664 is off-center
relative to its center of mass, and thus may generate a torque
(also referred to as a moment) about the center of mass of the base
1666 and/or the cover 1664. The base 1666 and/or the cover 1664 may
thus exhibit some rotation about its center of mass when being
pushed by the haptic actuator 621. Stated differently, when the
first spring component 1660A and the second spring component 1660B
have different spring constants, part of the base 1666 and/or the
cover 1664 may act as a lever when being pushed by the haptic
actuator 621. This lever configuration may be able to enhance a
haptic effect generated by the movement of the haptic actuator 621
and of the base 1666 and/or the cover 1664.
FIG. 17 illustrates an embodiment in which the pre-load, or more
specifically a compressive load, is created by integrating the
haptic actuator 621 into preexisting components of a haptic-enabled
device and further including a first spring component 1760A and a
second spring component 1760B to tune the resonant frequency of the
assembly. More specifically, FIG. 17 illustrates a sectional side
view of a haptic actuator assembly 1720 that includes the haptic
actuator 621 previously described above as well as a pre-load
device 1727. Although the haptic actuator assembly 1720 is shown
and described with the haptic actuator 621, any haptic actuator
described herein may also be utilized with the pre-load device
1727. The pre-load device 1727 is configured to create a
compressive load on the haptic actuator 621 along the axis 617, and
the compressive load opposes expansion, or more generally
deformation, of the haptic actuator 621 along the axis 617.
In the embodiment of FIG. 17, the pre-load device 1727 includes
components of a battery 1780 of a haptic-enabled device. However,
although the pre-load device 1727 is described with battery parts
or components, this is merely an example of how to implement the
haptic actuator assembly 1720 inside preexisting components of a
haptic-enabled device, and other preexisting components of the
haptic-enabled device may similarly be utilized. The battery 1780
includes a cover 1764 and a base 1766 spaced apart from and
extending parallel to the cover 1764. In an embodiment, the cover
1764 and/or the base 1766 of the battery 1780 may be a printed
circuit board. The battery 1780 is configured to house or contain
the haptic actuator 621, including both the layer 621a of
piezoelectric material and the displacement conversion device
621b-1/621b-2. The haptic actuator 621 is disposed between the
cover 1764 and the base 1766, with the cover 1764 and the base 1766
being disposed at respective opposite ends of the haptic actuator
621 along the axis 617 thereof. In an embodiment, the base 1766
supports the haptic actuator 621, or stated another way the haptic
actuator 621 is disposed on an interior surface of the base 1766.
In an embodiment, the base 1766 may be attached to the haptic
actuator 621 via an adhesive or some other manner of
attachment.
The first spring component 1760A is disposed such that a first end
1761A is coupled to an interior surface of the cover 1764 and a
second opposing end 1761B is coupled to an interior surface of the
base 1766. Similarly, the second spring component 1760B is disposed
such that a first end 1761C is coupled to the interior surface of
the cover 1764 and a second opposing end 1761D is coupled to the
interior surface of the base 1766. The first spring component 1760A
and the second spring component 1760B are shown as helical elements
for illustrative purposes only to represent the functional
operation thereof and this depiction is not intended to describe,
or limit, an actual physical shape thereof. The first spring
component 1760A and the second spring component 1760B may be any
type of spring element having the spring properties to tune the
resonant frequency of the haptic actuator assembly 1720 as
described in more detail below, including but not limited to
elastomers, helical or coiled springs, leaf springs, flat springs,
wave washers, snap dome springs, or a compliant element such as
rubber, foam, or flexures.
In the embodiment of FIG. 17, the base 1766 is configured to act as
a mechanical ground while the cover 1764 provides the mass required
to pre-load the haptic actuator 621. Stated another way, in this
embodiment, the mass of the cover 1764 is configured to create a
compressive load on the haptic actuator 621 along the axis 617, and
the compressive load opposes expansion of the haptic actuator 621
along the axis 617. The haptic actuator assembly 1720 can function
as a harmonic oscillator that runs at a relatively high frequency.
In operation, when a power source (not shown in FIG. 17) provides a
sinusoidal drive signal to the haptic actuator assembly 1720, the
haptic actuator 621 vibrates as directed by the oscillating drive
signal. More particularly, as described above with respect to the
operation of the haptic actuator 621, the displacement that is
output by the haptic actuator 621 along the axis 617 may come from
the expansion or contraction of the haptic actuator 621. The haptic
actuator assembly 1720 thus vibrates and provides haptic sensations
to the battery 1780 to which it is attached.
The haptic actuator assembly 1720 is configured to realize
mechanical resonance via the first spring component 1760A and the
second spring component 1760B. More particularly, the haptic
actuator 621 has a first resonant frequency and the haptic actuator
assembly 1720 has a second resonant frequency, the second resonant
frequency being different than the first resonant frequency. The
second resonant frequency is a function of or is determined via the
spring constants of the first spring component 1760A and the second
spring component 1760B. Due to the addition of the first spring
component 1760A and the second spring component 1760B, the total
spring constant of the haptic actuator assembly 1720 is different
than the spring constant of the haptic actuator 621 alone. As such,
the resonant frequency of the haptic actuator assembly 1720 varies
depending on the spring constants of each of the first spring
component 1760A and the second spring component 1760B and the
resonant frequency of the haptic actuator assembly 1720 may be
controlled by selecting particular or predetermined spring
components 1760A, 1760B. Stated another way, the first spring
component 1760A and the second spring component 1760B may be chosen
to change or alter the resonant frequency of the haptic actuator
621 alone such that the haptic actuator assembly 1720 has a desired
or predetermined resonant frequency in order to amplify the output
force and effects. By controlling the resonant frequency, the
haptic actuator assembly 1720 may be configured to resonate at a
certain frequency to present a wide spectrum of frequencies by
amplitude modulation techniques.
In an embodiment, an overall thickness of the haptic actuator
assembly 1720/1620/1520/1420/1320/1120 may be in a range of 2 mm to
10 mm.
In an embodiment, when a voltage difference of, e.g., 50 V to 100 V
is applied to two electrodes of a haptic actuator 621, and when the
compressive load or other pre-load is applied to the haptic
actuator 621 by the pre-load device 1727/1627/1527/1427/1327/1127,
the haptic actuator 621 outputs a displacement (relative to a
baseline state in which no voltage difference is being applied to
the haptic actuator 621) that is in a range of 5 .mu.m to 15 .mu.m,
and the haptic actuator assembly 1720/1620/1520/1420/1320/1120 is
configured to output a force along the axis 617 that is in a range
of 2N to 10 N.
In an embodiment, when the voltage difference being applied to the
haptic actuator 621 is, e.g., between 50 V and 100 V, and when the
compressive load is applied to the haptic actuator 621 by the
pre-load device 1727/1627/1527/1427/1327/1127, the haptic actuator
outputs a displacement (relative to the baseline state) that is in
a range of 25% to 50% of a defined nominal displacement for the
haptic actuator 621, wherein the nominal displacement may be
specific to the voltage difference. Further in this example, the
haptic actuator assembly 1720/1620/1520/1420/1320/1120 may be
configured to output a force along the axis 617 that is in a range
of 50% to 75% of a defined blocking force for the haptic actuator
621, wherein the blocking force may also be specific to the voltage
difference.
In an embodiment, the control unit 130/1130 may be configured to
generate a drive signal for the haptic actuator 621 that is at a
resonant frequency of the respective haptic actuator assembly
1720/1620/1520/1420/1320/1120. In an embodiment, the drive signal
may have an amplitude (e.g., peak-to-peak amplitude) that is below
a defined threshold, in order to further avoid generating excessive
force or displacement that would damage the haptic actuator, even
with the presence of a pre-load.
In an embodiment, the control unit 130/1130 may be configured to
generate a drive signal with a frequency content that includes at
least a first frequency that is a resonant frequency of the haptic
actuator assembly 1720/1620/1520/1420/1320/1120 and a second
frequency that is not the resonant frequency of the haptic actuator
assembly 1720/1620/1520/1420/1320/1120. In other words, the drive
signal may include a first component having the first frequency and
a second component having the second frequency. In some cases, the
first component and the second component may be the only
frequencies of the drive signal. The control unit 130/1130 may
cause the first component of the drive signal to have a first
amplitude that is below the defined threshold (because the first
component has the resonant frequency), and may cause the second
component to have a second amplitude that is higher than the first
amplitude and above the defined threshold.
Additional discussion of various embodiments is presented
below:
Embodiment 1 is a haptic actuator assembly, comprising: a haptic
actuator and a pre-load device. The haptic actuator includes a
layer of piezoelectric material configured to generate strain along
a parallel axis, the parallel axis being parallel to a planar
surface of the layer, and includes a displacement conversion device
configured to convert the strain of the layer of piezoelectric
material along the parallel axis to expansion or contraction of the
haptic actuator along a perpendicular axis, the perpendicular axis
being perpendicular to the planar surface of the layer. The
expansion or contraction of the haptic actuator is configured to
generate a displacement of the haptic actuator along the
perpendicular axis.
The pre-load device is adjacent to the haptic actuator and
configured to generate a compressive load on the haptic actuator
along the perpendicular axis. The pre-load device includes a casing
having a cover and a base spaced apart from and extending parallel
to the cover. The haptic actuator is disposed between the cover and
the base, the cover and the base being disposed at respective
opposite ends of the haptic actuator along the perpendicular axis
thereof. A first spring component is disposed within the casing
such that a first end of the first spring component is coupled to
an interior surface of the cover and a second opposing end of the
first component is coupled to an outer surface of the haptic
actuator. The first spring component is configured to exert a force
in order to create the compressive load on the haptic actuator
along the perpendicular axis.
Embodiment 2 includes the haptic actuator assembly of embodiment 1,
wherein the displacement conversion device of the haptic actuator
is a displacement amplification device configured to convert a
displacement output by the layer of piezoelectric material along
the parallel axis due to the strain thereof to a greater
displacement of the haptic actuator along the perpendicular
axis.
Embodiment 3 includes the haptic actuator assembly of embodiment 2,
wherein the displacement amplification device of the haptic
actuator includes a lever device configured to convert the
displacement along the parallel axis to the greater displacement
along the perpendicular axis.
Embodiment 4 includes the haptic actuator assembly of embodiment 3,
wherein the lever device of the haptic actuator includes a first
disc and a second disc disposed on respective opposite planar
surfaces of the layer of piezoelectric material, wherein each disc
of the first disc and the second disc forms a truncated cone with a
respective planar surface of the layer of piezoelectric
material.
Embodiment 5 includes the haptic actuator assembly of any one of
embodiments 1-4, wherein the first spring component is a spring
plunger.
Embodiment 6 includes the haptic actuator assembly of any one of
embodiments 1-4, wherein the first spring component includes a
screw and a flexible film component, the screw being configured to
adjust a spring force of the flexible film component.
Embodiment 7 includes the haptic actuator assembly of any one of
embodiments 1-6, wherein the pre-load device further includes a
second spring component disposed within the casing such that a
first end of the second spring component is coupled to an interior
surface of the base and a second opposing end of the second spring
component is coupled to an outer surface of the haptic actuator.
The first spring component and the second spring component are
configured to collectively exert the force in order to create the
compressive load on the haptic actuator along the perpendicular
axis.
Embodiment 8 includes the haptic actuator assembly of embodiment 7,
wherein the first spring component has a first spring constant and
the second spring component has a second spring constant, the first
spring constant being different than the second spring
constant.
Embodiment 9 includes the haptic actuator assembly of any one of
embodiments 1-8, wherein the compressive load along the
perpendicular axis generated by the first component and the second
component of the pre-load device is in a range of 2 N to 4 N.
Embodiment 10 includes the haptic actuator assembly of any one of
embodiments 1-9, wherein the haptic actuator further comprises at
least two electrodes attached to or embedded within the layer of
piezoelectric material and configured to create a voltage
difference along the perpendicular axis. The layer of piezoelectric
material is configured to contract along the parallel axis in
response to the voltage difference along the perpendicular
axis.
Embodiment 11 includes the haptic actuator assembly of embodiment
10, wherein when the voltage difference between the at least two
electrodes is between 50 V and 100 V and when the compressive load
is applied to the haptic actuator by the pre-load device, the
haptic actuator outputs a displacement along the perpendicular
axis, relative to a baseline state in which there is no voltage
difference between the at least two electrodes, that is in a range
of 1 .mu.m to 15 .mu.m, and the haptic actuator assembly is
configured to output a force along the perpendicular axis that is
in a range of 2N to 10 N.
Embodiment 12 includes the haptic actuator assembly of any one of
embodiments 1-11, wherein the haptic actuator has a first resonant
frequency and the haptic actuator assembly has a second resonant
frequency, the second resonant frequency being different than the
first resonant frequency and the second resonant frequency being
determined via a spring constant of the first spring component.
Embodiment 13 is a haptic actuator assembly, comprising: a haptic
actuator and a pre-load device. The haptic actuator includes a
layer of piezoelectric material configured to generate strain along
a parallel axis, the parallel axis being parallel to a planar
surface of the layer, and includes a displacement conversion device
configured to convert the strain of the layer of piezoelectric
material along the parallel axis to expansion or contraction of the
haptic actuator along a perpendicular axis, the perpendicular axis
being perpendicular to the planar surface of the layer. The
expansion or contraction of the haptic actuator is configured to
generate a displacement of the haptic actuator along the
perpendicular axis.
The pre-load device is adjacent to the haptic actuator and
configured to generate a compressive load on the haptic actuator
along the perpendicular axis. The pre-load device includes a casing
having a cover, a base spaced apart from and extending parallel to
the cover, a first spring component, and a second spring component.
The first spring component and the second spring component are
disposed at respective opposite ends of the cover and each of the
first spring component and the second spring component extends
between the cover and the base. The first spring component and the
second spring component are configured to collectively exert a
force in order to create the compressive load on the haptic
actuator along the perpendicular axis. The haptic actuator is
disposed between the cover and the base, the cover and the base
being disposed at respective opposite ends of the haptic actuator
along the perpendicular axis thereof.
Embodiment 14 includes the haptic actuator assembly of embodiment
13, wherein the first spring component and the second spring
component are attached to the cover and are releasably attached to
the base.
Embodiment 15 is a haptic-enabled device comprising: a housing, a
power source, and a haptic actuator assembly configured to generate
a haptic effect at an outer surface of the housing. The haptic
actuator includes a layer of piezoelectric material configured to
generate strain along a parallel axis, the parallel axis being
parallel to a planar surface of the layer, and includes at least
two electrodes attached to or embedded within the layer of
piezoelectric material, and includes a displacement conversion
device configured to convert the strain of the layer of
piezoelectric material along the parallel axis to expansion or
contraction of the haptic actuator along a perpendicular axis, the
perpendicular axis being perpendicular to the planar surface of the
layer. The expansion or contraction of the haptic actuator is
configured to generate a displacement of the haptic actuator along
the perpendicular axis.
The pre-load device is adjacent to the haptic actuator and
configured to generate a compressive load on the haptic actuator
along the perpendicular axis. The pre-load device includes a casing
having a cover and a base spaced apart from and extending parallel
to the cover. The haptic actuator is disposed between the cover and
the base, the cover and the base being disposed at respective
opposite ends of the haptic actuator along the perpendicular axis
thereof. A first spring component is disposed within the casing
such that a first end of the first spring component is coupled to
an interior surface of the cover and a second opposing end of the
first component is coupled to an outer surface of the haptic
actuator. The first spring component is configured to exert a force
in order to create the compressive load on the haptic actuator
along the perpendicular axis.
The haptic-enabled device further comprises a control unit
configured to control the power source to provide power to the at
least two electrodes of the haptic actuator.
Embodiment 16 includes the haptic-enabled device of embodiment 15,
wherein any compressive load applied to the haptic actuator
assembly by the housing of the haptic-enabled device is less than 1
N.
Embodiment 17 includes the haptic-enabled device of any one of
embodiments 15-16, further comprising a touch screen device that
forms a first side of the housing. The housing comprises a back
panel that forms a second and opposite side of the housing. The
haptic actuator assembly is disposed at the second side of the
housing, so that force generated by the haptic actuator assembly is
exerted against the second side of the housing.
Embodiment 18 includes the haptic-enabled device of any one of
embodiments 15-17, wherein the control unit is configured to
control the power source to provide a drive signal to the haptic
actuator and wherein the drive signal is a periodic signal having a
frequency equal to a resonant frequency of the haptic actuator
assembly.
Embodiment 19 includes the haptic-enabled device of any one of
embodiments 15-18, wherein the haptic actuator has a first resonant
frequency and the haptic actuator assembly has a second resonant
frequency, the second resonant frequency being different than the
first resonant frequency and the second resonant frequency being
determined via a spring constant of the first spring component.
Embodiment 20 includes the haptic-enabled device of any one of
embodiments 15-19, wherein the pre-load device further includes a
second spring component disposed within the casing such that a
first end of the second spring component is coupled to an interior
surface of the base and a second opposing end of the second spring
component is coupled to an outer surface of the haptic actuator,
the first spring component and the second spring component being
configured to collectively exert the force in order to create the
compressive load on the haptic actuator along the perpendicular
axis.
While various embodiments have been described above, it should be
understood that they have been presented only as illustrations and
examples of the present invention, and not by way of limitation. It
will be apparent to persons skilled in the relevant art that
various changes in form and detail can be made therein without
departing from the spirit and scope of the invention. Thus, the
breadth and scope of the present invention should not be limited by
any of the above-described exemplary embodiments, but should be
defined only in accordance with the appended claims and their
equivalents. It will also be understood that each feature of each
embodiment discussed herein, and of each reference cited herein,
can be used in combination with the features of any other
embodiment. All patents and publications discussed herein are
incorporated by reference herein in their entirety.
* * * * *